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Container Soils - Water Movement & Retention IV

12 years ago

A thread similar to this has been posted three other times. Each of the other postings have reached the maximum allowable - 150 replies. I would like to preface this post by saying that over the last few years, the thread & subject has garnered a fair amount of attention that has been evidenced by the many, many e-mails I find in my in-box, and has been a wonderful catalyst in the forging of new friendships and in increasing my list of acquaintances with similar growing interests. I welcome these exchanges, which alone are enough to make me hope the subject continues to pique interest and curiosity. Not an afterthought, I should add that there is equal satisfaction in the knowledge that some of the information provided in good-spirited exchange is making a significant difference in some growers' success.

I'll provide links to the previous three threads at the end of what I have written. Thank you for looking into this subject - I hope that any/all who read it take something interesting and helpful from it. I know it's long, but I hope you find it worth the read.


Container Soils - Water Movement and Retentionsize>

As container gardeners, our first priority should be to insure the soils we use are adequately aerated for the life of the planting, or in the case of perennial material (trees, shrubs, garden perennials), from repot to repot. Soil aeration/drainage is the most important consideration in any container planting. Soil is the foundation that all container plantings are built on, and aeration is the cornerstone of that foundation. Since aeration and drainage are inversely linked to soil particle size, it makes good sense to try to find and use soils or primary components with particles larger than peat. That components retain their structure for extended periods is also extremely important. Pine and some other types of conifer bark fit the bill nicely and Ill talk more about them later.

The following also hits pretty hard against the futility of using a drainage layer in an attempt to improve drainage. It just doesn't work. All it does is reduce the amount soil available for root colonization. A wick will remove water from the saturated layer of soil at the container bottom. It works in reverse of the self-watering pots widely being discussed on this forum now.

Since there are many questions about soils appropriate for use in containers, I'll post my basic mix later, in case any would like to try it. It will follow the Water Movement info.

Consider this if you will:

Soil need fill only a few needs in plant culture. Anchorage - A place for roots to extend, securing the plant and preventing it from toppling. Nutrient Sink - It must retain sufficient nutrients in available form to sustain plant systems. Gas Exchange - It must be sufficiently porous to allow air to the root system and by-product gasses to escape. And finally, Water - It must retain water enough in liquid and/or vapor form to sustain plants between waterings. Most plants could be grown without soil as long as we can provide air, nutrients, and water, (witness hydroponics). Here, I will concentrate primarily on the movement of water in soil(s).

There are two forces that cause water to move through soil - one is gravity, the other capillary action. Gravity needs little explanation, but for this writing I would like to note: Gravitational flow potential (GFP) is greater for water at the top of the container than it is for water at the bottom. I'll return to that later. Capillarity is a function of the natural forces of adhesion and cohesion. Adhesion is water's tendency to stick to solid objects like soil particles and the sides of the pot. Cohesion is the tendency for water to stick to itself. Cohesion is why we often find water in droplet form - because cohesion is at times stronger than adhesion, waterÂs bond to itself can be stronger than the bond to the object it might be in contact with; in this condition it forms a drop. Capillary action is in evidence when we dip a paper towel in water. The water will soak into the towel and rise several inches above the surface of the water. It will not drain back into the source. It will stop rising when the GFP equals the capillary attraction of the fibers in the paper.

There will be a naturally occurring "perched water table" (PWT) in containers when soil particulate size is under about .125 (1/8) inch.. This is water that occupies a layer of soil that is always saturated & will not drain from the portion of the pot it occupies. It can evaporate or be used by the plant, but physical forces will not allow it to drain. It is there because the capillary pull of the soil at some point will surpass the GFP; therefore, the water does not drain, it is "perched". The smaller the size of the particles in a soil, the greater the height of the PWT.

If we fill five cylinders of varying heights and diameters with the same soil mix and provide each cylinder with a drainage hole, the PWT will be exactly the same height in each container. This saturated area of the pot is where roots seldom penetrate & where root problems frequently begin due to a lack of aeration. Water and nutrient uptake are also compromised by lack of air in the root zone. Keeping in mind the fact that the PWT height is soil dependent and has nothing to do with height or shape of the container, we can draw the conclusion that: Tall growing containers will always have a higher percentage of unsaturated soil than squat containers when using the same soil mix. The reason: The level of the PWT will be the same in each container, with the taller container providing more usable, air holding soil above the PWT. Physiology dictates that plants must have oxygen at the root zone in order to maintain normal root function.

A given volume of large soil particles has less overall surface area when compared to the same volume of small particles and therefore less overall adhesive attraction to water. So, in soils with large particles, GFP more readily overcomes capillary attraction. They drain better. We all know this, but the reason, often unclear, is that the height of the PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. Mixing large particles with small is often very ineffective because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential.

When we add a coarse drainage layer under our soil, it does not improve drainage. It does though, conserve on the volume of soil required to fill a pot and it makes the pot lighter. When we employ this exercise in an attempt to improve drainage, what we are actually doing is moving the level of the PWT higher in the pot. This simply reduces the volume of soil available for roots to colonize. Containers with uniform soil particle size from top of container to bottom will yield better and more uniform drainage and have a lower PWT than containers with drainage layers. The coarser the drainage layer, the more detrimental to drainage it is because water is more (for lack of a better scientific word) reluctant to make the downward transition because the capillary pull of the soil above the drainage layer is stronger than the GFP. The reason for this is there is far more surface area for water to be attracted to in the soil above the drainage layer than there is in the drainage layer, so the water "perches".

I know this goes against what most have thought to be true, but the principle is scientifically sound, and experiments have shown it as so. Many nurserymen are now employing the pot-in-pot or the pot-in-trench method of growing to capitalize on the science.

If you discover you need to increase drainage, you can simply insert an absorbent wick into a drainage hole & allow it to extend from the saturated soil to a few inches below the bottom of the pot, or allow it to contact soil below the container where it can be absorbed. This will successfully eliminate the PWT & give your plants much more soil to grow in as well as allow more, much needed air to the roots.

Uniform size particles of fir, hemlock or pine bark are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as natureÂs preservative. Suberin is what slows the decomposition of bark-based soils. It contains highly varied hydrocarbon chains and the microorganisms that turn peat to soup have great difficulty cleaving these chains.

In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they starve/"suffocate" because there is insufficient air at the root zone to insure normal water/nutrient uptake and root function.

To confirm the existence of the PWT and the effectiveness of using a wick to remove it, try this experiment: Fill a soft drink cup nearly full of garden soil. Add enough water to fill to the top, being sure all soil is saturated. Punch a drain hole in the bottom of the cup & allow to drain. When the drainage stops, insert a wick into the drain hole . Take note of how much additional water drains. Even touching the soil with a toothpick through the drain hole will cause substantial additional water to drain. This is water that occupied the PWT before being drained by the wick. A greatly simplified explanation of what occurs is: The wick "fools" the water into thinking the pot is deeper, so water begins to move downward seeking the "new" bottom of the pot, pulling the rest of the water in the PWT along with it. If there is interest, there are other simple and interesting experiments you can perform to confirm the existence of a PWT in container soils. I can expand later.

I remain cognizant of these physical principles whenever I build a soil. I havenÂt used a commercially prepared soil in many years, preferring to build a soil or amend one of my 2 basic mixes to suits individual plantings. I use many amendments when building my soils, but the basic building process starts with conifer bark and perlite. Sphagnum peat usually plays a minor, or at least a secondary role in my container soils because it breaks down too quickly and when it does, it impedes drainage and reduces aeration.

Note that there is no sand or compost in the soils I use. Sand, though it can improve drainage in some cases, reduces aeration by filling valuable macro-pores in soils. Unless sand particle size is fairly uniform and/or larger than about ½ BB size I leave it out of soils. Compost is too unstable for me to consider using in soils. The small amount of micronutrients it supplies can easily be delivered by one or more of a number of chemical or organic sources.

My Basic Soil

I'll give two recipes. I usually make big batches. I also frequently add agricultural sulfur to some soils for acid-lovers or to soils I use dolomitic lime in.

5 parts pine bark fines

1 part sphagnum peat (not reed or sedge peat please)

1-2 parts perlite

garden lime or gypsum

controlled release fertilizer

micronutrient powder (or other continued source of micronutrients)

Big batch:

3 cu ft pine bark fines (1 big bag)

5 gallons peat

5 gallons perlite

2 cups lime or gypsum (you can add more to small portion if needed)

2 cups CRF

1/2 cup micronutrient powder (or other)

Small batch:

3 gallons pine bark

1/2 gallon peat

1/2 gallon perlite

small handful lime or gypsum

1/4 cup CRF

1 tbsp micro-nutrient powder

I have seen advice that some highly organic (practically speaking - almost all are highly organic) container soils are productive for up to 5 years or more. I disagree and will explain why if there is interest. Even if you were to substitute fir bark for pine bark in this recipe (and this recipe will long outlast any peat based soil) you should only expect a maximum of two to three years life before a repot is in order. Usually perennials, including trees (they're perennials too, you know) ;o) should be repotted more frequently to insure vigor closer to their genetic potential. If a soil is desired that will retain structure for long periods, we need to look more to inorganic components. Some examples are crushed granite, pea stone, coarse sand (see above - usually no smaller than ½ BB size in containers, please), Haydite, lava rock (pumice), Turface or Schultz soil conditioner, and others.

Al Fassezke

If there is interest, please find the previous postings here:

Posting I

Posting II

Posting III

Comments (150)

  • tapla

    Hi, Jodi - You're welcome. ;o) glad to hear all's well with your plants, and especially that you're doing OK after the bump.

    Sounds like you've got everything under control. Congrats - I know you work hard at keeping up with all that's associated with attending to all your plants. Take good care.

    Glad you like the STEM, too ....


  • succulentlover

    Thanks for the quick reply Tapla.
    Im going to try and make a batch this weekend. There is a garden center that carries a good variety of items in small sizes and bulk. I do have some questions about the ingredients.

    1. Does it matter what kind of turface I get or should I look for the MVP since that is what seems to be used most?

    2. Is there any pro and con to the different kinds of bark? Would there be any reason to look for one over the other?

    3. Am I using the sand mainly for the silica? If so can I use Diatomite instead? It says that it is 90% silicon dioxide and has a slow release of silica. My mom uses it for her orchids so it's readily available to me.

    4. Is there something I can substitute the vermiculite with or just not use it at all? You mentioned in another post that it breaks down and compacts quickly and that I can provide the Mg and Ca in other ways.

    5. I assume the difference between dolomitic lime and regular lime is that the regular stuff is a powder form and will just go to the bottom of the mixture. I also assume that I am using the lime or gypsum to raise the pH. If so, I am just curious what is making the mixture acidic. I know that peat is acidic and most peat mixes need lime to help bring it to a neutral pH.

    6. And lastly, :), I see that you didn't say to use any CRF and just micronutrients. Why wouldn't I need to any CRF. I was also wondering if you have ever heard of ZeoPro? My mom ordered some and according to the literature on the stuff it provides a "complete suite of minor and trace nutrients". I am almost positive that this is in a granular form, but it may be a powder. I should know for sure this week.

    Thank you so much for the help and information. I am quite excited to give this a try!! :)


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  • tapla

    1. Does it matter what kind of turface I get or should I look for the MVP since that is what seems to be used most?

    Yes - use MVP only. I mentioned that several times upthread, but I often forget to add the 'MVP' later, taking it for granted that you know. Sorry about that. ;o)

    2. Is there any pro and con to the different kinds of bark? Would there be any reason to look for one over the other?

    I've used southern yellow pine, fir, and hemlock bark - all with good results. The SYP will be easiest to find. As long as it's conifer bark, particle size will be the primary consideration.

    3. Am I using the sand mainly for the silica? If so can I use Diatomite instead? It says that it is 90% silicon dioxide and has a slow release of silica. My mom uses it for her orchids so it's readily available to me.

    Actually, I use it for it's physical properties. It seems to tighten the soil w/o any compacting, and provides additional surface area to hold water for short periods w/o supporting a PWT. It serves the same purpose as crushed granite, except it's finer. You can do without it if you choose. The diatomite comes in lots of varieties/types (raw, calcined, flux-calcined) so I really couldn't say. I'm guessing though that there would be little difference between that & Turface, except that calcined diatomaceous earth is generally even more porous than Turface & has a higher CEC. Since the silica wasn't being added to the soil for its porosity - if you choose to add the CDE, you'll probably want to reduce the amount of Turface in the mix accordingly.

    4. Is there something I can substitute the vermiculite with or just not use it at all? You mentioned in another post that it breaks down and compacts quickly and that I can provide the Mg and Ca in other ways.

    You can leave that out too, if you wish. There is nothing carved in stone. The recipe is just a mix that I've been using for a long time, and one I've provided to other succulent growers who really liked it, and the feedback from them has been exceedingly favorable. It's no accident that the vermiculite is about 9% of the total mix. I do use it occasionally in soils, and have found it a very good addition to the recipe I offered. There will be no compaction if you keep the total volume down around 10%.

    5. I assume the difference between dolomitic lime and regular lime is that the regular stuff is a powder form and will just go to the bottom of the mixture. I also assume that I am using the lime or gypsum to raise the pH. If so, I am just curious what is making the mixture acidic. I know that peat is acidic and most peat mixes need lime to help bring it to a neutral pH.

    The pelletized lime is prilled powder, so it dissolves quickly, too. You should incorporate it into damp soil when you are mixing it. Much of it will be retained in the micropores of the Turface and bark, and some in the minute surface irregularities of the rest of the particulates. In the recipe above, I'd probably choose to add gypsum instead of lime (unless you use a Ca/Mg supplement like Botanicare Cal-Mag Plus when you fertilize). The pH of the above soil will come in around 6.5 or so, so if you wish to stay south of a pH of 7 (neutral) you should use the gypsum, which doesn't affect pH. If you use the gypsum, make sure your plants are getting Mg, because gypsum won't supply it.

    6. And lastly, :), I see that you didn't say to use any CRF and just micronutrients. Why wouldn't I need to any CRF. I was also wondering if you have ever heard of ZeoPro? My mom ordered some and according to the literature on the stuff it provides a "complete suite of minor and trace nutrients". I am almost positive that this is in a granular form, but it may be a powder. I should know for sure this week.

    I didn't suggest a fertilizer because you said "terrariums", so I thought you would have a favorite. Also, I notice more salt build-up when I use CRFs, and I knew that you wouldn't care for that in an enclosed terrarium. Perhaps I missed something?

    There's been lots of hype about ZeoPro & the space program, but really, it's just clinoptilolite (a naturally occurring form of zeolite). It's often used as a soil treatment. Its primary value is as a slow release source of K, but if it was treated with ammonium during manufacture, it can similarly serve as a slow release store of nitrogen. Neither of these benefits seem particularly impossible to do without to me (just add N at will or include a little potash when you make your soils for the extra K kick if you think it's needed. Their website makes some pretty outrageous claims "... has intelligence that actually communicates with your plants ...", reminding me of Superthrive.

    More important though than it's chemical claims is its physical characteristics - its particle size. If you think it's the right size for one of the soil components, substitute it or add it if you choose. If it's really porous - sub for Turface - if not so porous, sub for the granite.

    Take care. ;o)


  • succulentlover

    Thanks so much Al, for answering all those questions.

    I am going to have to make a shopping list of different possibilities and see what's available at the store. But I have more reading to do first.

    Right now I have four terrariums. I have only been making them for a year since I saw some at the Philly flower show. I've read and have been told to fertilize very very sparingly so the plants don't outgrow the terrarium. So, to say the least, I have yet to fertilize a single one, and most of my other plants as well.

    Here is a link to my terrarium album:

    I also have pictures of most of my succulents on there as well, which I only fertilized once, and I screwed that up. After I watered all of my succulents a couple of times with Jacks Classic 20-20-20, ALL of my pots started to get covered in white build-up. I originally thought it was mold/fungus because I was watering with dehumidifier water (another long story :). It of course turned out to be a build up of minerals leeching out of the clay pots. I have yet to fertilize them again.

    BTW, I buy a special mix for my succulents made at another garden center that looks similar to your mix in the middle of the picture above, just more rocky.

    I found your post about the "Fertilizer Program". That will be my reading for tomorrow, because I really need to understand how to fertilize properly, since all I ever use is the 20-20-20 ;)

    When I first started growing plants three years ago, I never realized how much there could be to it, but I still love it!

    Thanks you again


  • succulentlover

    I forgot something important. The reason why I asked if I should put CRF in the mix is because the MiracleGro soil has some three month stuff in it. So the plants have food for a little while when I first put them in. I'm sure a couple of them could use some food, like the first one I made almost a year ago, but I am worried that I will hurt the plants more then help.


  • tapla

    Strong work, Ross. You've done a really nice job. I'm impressed. ;o)

    I don't think I'd use the CRF. I think you should try to maintain closer control of your nutrient supplementation than you could if you just add CRF. Please do read the fertilizer thread. Pay particular attn to the thoughts about high P fertilizers like those with a 1:1:1 ratio. Plants use about 6 times more N than P when both are in the adequacy range, so 1:1:1 fertilizers supply about 6 times the P plants use. That translates to lots of extra salt accumulation in your soils. If you are supplying all the other nutrients, you can limit growth by reducing the amount of N you supply.

    Lets go back to the ZeoPro you were talking about for a sec. If you included it in your soils, it would serve best as a slow release provider of K, and possibly N if it was so treated. Plants use about 3-1/2 times as much K as P, so if you fertilized sparingly with 0-10-10, you could pretty much control vegetative growth with how much additional N you provide while furnishing approx the correct ratio of both P & K. Are you with me?


  • succulentlover

    Thanks for the compliments ^^

    Im not sure if I am with you or not. I've been reading all night again tho.
    So, if I was to not use the ZeoPro, then I would want to go with a 0-10-20 and provide the N as need be? Let's say I want to grow the plants for a few months, then slow them down, I would then use a regular fert with the 3:1:2 and then once I want to slow the plants down, decrease the N considerably? And not worry about the micronutrients right away since I've put the granules in the soil mix? Are there products that add only P and K, and then something else to just add N? I feel like I am back in chemistry class!

    I read the fert. thread and I know one thing for certain, I need to find some good literature, there is definitely a lot more then just planting, watering and feeding (which I royally screwed up). I can't tell you how many people have told me to just use a 20-20-20 to be safe :(

    I did find some sites on how to diagnose different nutrient deficiencies in plants, so that should be a start in understanding the needs of each nutrient.

    Also, how important is it to know the TDS and pH of my tap water? I only use distilled water in my terrariums, but I use tap for everything else. I researched my water departments water analysis but they don't list the TDS. Is it worth having tested? I use a pH test kit for fresh water aquariums on my tap and it shows about 6.8-7.2, but I don't know how reliable these kits are. I just want to be able to take care of my plants as best as I can ^^

    Thanks so much

  • kristimama

    Wow! I went looking for information for potting my new dwarf citrus and ended up here. A lot of great info to take in and try to understand.

    I was really, truly hoping I'd find some easy, out of the bag product to buy. I'll admit.. I'm a lazy newbie gardener who just wants to grow some fruit in pots and teach my kids about the wonder of gardening... never did I think I'd end up seriously concocting my own home-brew soil. And now I'm so excited about doing it I can't wait to hose out my wheelbarrow and get started. LOL

    That said, I want to push back and ask you about 3 things:

    1) Your mix is so contrary to what all my local independent nurseries (I've asked at 3 different places) and even to what the folks at Four Winds recommend, I am needing some extra convincing. Maybe it's how I'm "wired" to really understand something well before proceeding.

    You've probably addressed this before, but I'm very new to GW and have only posted a couple times at the Citrus Forum, so please bear with me.

    The guys at Four Winds, in their own materials, say:
    "Use a soil mix that is lightweight and drains well. If the mix is dense or contains peat moss, amend your soil mix with 1/4-1/3 volume of 1" redwood shavings."

    They're saying to use one of the commercially available potting mixes... which from your write-up would be a HUGE no-no.

    And they recommend adding "redwood shavings" rather than pine. Is there a difference? Is either of these things the "gorilla hair" that I see in new landscaping as a mulch?

    And in a separate email with someone at Four WInds, he told me I could also use Cedar chips, because they repel the ants better. And if I'm understanding your info, chips of any size would be bad because they will ultimately decompose and collapse the soil, right?

    Also I'm confused about why a company that sells citrus would deliberately encourage their customer base to plant their potted citrus in something that will cause their plants to fail, and fairly soon it seem like judging from the high rate of failure I have seen on the citrus forum.

    Yet every nursery specialist that I have talked to tells me to use potting soil---and they all look at me like I have 3 heads when I start talking about home-brewing my own soil/potting mix.

    Is it possibly that they expect most people to pot a citrus, spend a year or 2 before it dies, then buy a new one?

    2) My second sort of question, concern really... deals with whether the mix you're recommending is "organic" or geared to "green gardening"... so to speak. I completely understand why not to throw a bunch of organic matter into the mix (because it will compact the soil)... but on the flip side of this there have been a lot of materials listed in this post that are new to me. Are they chemicals? Do they leach into the food. Does the Turface MVP stuff have, say, petrochemical residue from the manufacturing process? I'm not just trying to grow lush beautiful plants... I want to be able to eat them and trust that they, themselves, are "organically" grown. Does your mix fit within those sorts of loose paramaters.

    I hope I don't sound like a crazy cook... but I'm the first to admit I'm of the granola-crunchy California persuasion. I'm not far from Berkeley here. LOL

    3) And finally, you mention that your mix is great for succulents. Do you have a specific mix for potting citruses?

    Thank you very much,

  • tapla

    Hi, Ross & Kristi. I have to go keep the wolf away (work), but I'll answer later. Such a skeptic, Christie. (big grin - playing off your admission) I can't wait to get to your reply. ;o)


  • meyermike_1micha

    Kristi.........I was told the same thing by Four Winds and I have been dealt the same way by my local greenhouse!!!
    Never thought to ask the way you did..I am sure Al will have a great anwer as soon as he thinks this one over!!!
    Looking forward to your thoughts AL.;:)

  • kristimama

    MeyereMike, I have been asking this everywhere, too. I even asked on the citrus forum (half in jest) if Four Winds would just sell the stuff they use in their black pots.

    AL... two more questions if you have it in ya...

    1) What kind of Pots???? This is my first time growing citrus (or anything other than anuals in small pots). I was surprised on the citrus forum to see so many people growing in plastic pots and many even using the commercial black plastic.

    I guess there are pros and cons of both.

    Terra cotta = breathes better but is darn heavy.

    Plastic = doesn't breathe as well and roots might get hotter in summer, but they are so much easier to move around and easier to work with when planting up, which is a given if I'm lucky enough to have my citrus thrive.

    Is your mix particularly suited to plastic since it seems like it drains extraordinarily fast?

    And if so, would you add more organic material if you were using terra cotta?

    I'm in the SF Bay Area, about an hour inland... and we get about a month of some very scorching summer days and I'm afraid the plastic pots will deteriorate and bake the roots. And I don't particularly like the look of them. So I'm still on the fence about what to use.

    2) My second question has to do with growing blueberries in a pot. That'll be the next thing I plant this spring, and my nursery gave me a handout with instructions to use 1/3 pathway bark, 1/3 peat moss, and 1/3 leaf mold plus 2 TBS of Soil Sulfur. What do you think of that mix---for blueberries, that is.

    And yes, I am a bit of a skeptic and am eagerly awaiting your repsonse.

    Thank you very much for the time and dedication you put into helping all of us here.


  • kristimama

    Ooh-ooh-ooooh! (Arm raised in the air like Horshack on Welcome Back Cotter.)

    It seems like the more I learn---and the more I start thinking this all through---more questions occur to me.

    These questions are both specific to me planting citrus... but I'm guessing that the science behind the soil/aeration is about the same.

    1) I am considering potting a standard Satsuma tree (i.e. non-dwarf). I've been told repeatedly that one of the main reasons to only pot up 1 size (only a couple inches bigger than current size) is so not to drown the plant with too much soil.

    Since your mix has such incredible drainage, would it stand to reason that I could actually go up maybe two pot sizes, or more? Have you personally tried this? I am mainly asking about the larger satsuma, because I'd like to get it into the largest, stablest terra cotta pot I can now so that I can let it stay there a while. With my dwarf's, I'm resigned to having to start small and pot up slowly... though if you told me this soil would facilitate a larger pot that would be nice, too. I just don't want to be transplanting a standard tree every other year.

    2) Speaking of my dwarf's, using your formula, about how quickly would you think they stay in one pot before going up to the next pot size. I vagely recall in this or one of your other posts, you mentioning you're potting up every year? Does this potting mix help make plants grow faster & bigger? (At this point, I'd be happy with just keeping them alive. But a girl can dream, right? LOL)

    THANK YOU again! Can't wait to see your responses to my many questions. And I hope it's not a bore to those of you reading who are already advanced using this information. Don't mean to hog the board with MY questions.

  • kristimama

    Aaaack... I started reading the OTHER Al/Tapla posts...

    and, if I'm reading it all correctly, I've stumbled on something seemed contradictory to me:
    A) Needing more frequent watering as a result of improved drainage, and B) incompatability with drip irrigation systems.

    1) Needing more frequent watering. This mix, and Al's and other people description of how it works, SOUNDS like it needs daily watering. In one of the 150 +posts, someone named Untitled pushed hard that he couldn't do daily watering.

    And seemingly contradictory... I THINK I saw a post that this mix doens't work well with drip irrigation systems, which is probably what I will eventually put these on after I figure out their watering needs.

    So Al... if I were someone who couldn't guarantee a daily watering and might want to space that just a little----but still benefit from all the theoretical improvements you're recommending... are there adjustments you can make to the mix to make it hold water better, while still being well draining? I'm hoping you have already experimented with this before, or at least been asked about it.

    And, yes, ONE MORE questions...

    I have a couple of half-used bags of the potting mix my local nursery recommends for everything (and I've got all my flowering annuals in it now). I'd like to use as much of it as I can because it wasn't cheap.

    Would you be able to look at the description below and see if I could mix it with the right things to give it the same or similar draining properties of YOUR mix?

    It's called "Gardener's Gold" from Master Nursery:

    "Gardeners Gold[tm] Organic Potting Soil - 2 Cubic Feet
    A rich, all natural blend of finely screened, composted fir bark fines, worm castings, real topsoil, redwood peat moss, chicken manure, and sand. pH balanced with dolomite and oyster shell limes. Rich in long-lasting plant nutrients. Water saving formula. Provides excellent drainage. Good for all indoor or outdoor container plants."

    Like, could I maybe add perlite or turface and give it a go?

    Or should I just chuck it into the yard?

    THANKS again and again and again.

  • tapla

    Ross - You wrote So, if I was to not use the ZeoPro, then I would want to go with a 0-10-20 and provide the N as need be? Let's say I want to grow the plants for a few months, then slow them down, I would then use a regular fert with the 3:1:2 and then once I want to slow the plants down, decrease the N considerably? And not worry about the micronutrients right away since I've put the granules in the soil mix? Are there products that add only P and K, and then something else to just add N?

    Your 0-10-20 idea is pretty close. Any fertilizer with a P:K ratio of about 1:2 that is low in N (an example might something like a 5-10-20) will be a good choice to keep growth contained. Some growth is necessary though, to prevent decline. On the flip side, if you want the plant to experience closer to a normal growth pattern, the 3:1:2 ratios should work very well & I would rate them the best o/a choice.

    ... how important is it to know the TDS and pH of my tap water? ... Is it worth having tested? I use a pH test kit for fresh water aquariums on my tap and it shows about 6.8-7.2, but I don't know how reliable these kits are.

    It's just nice to have a good idea, if you're fertilizing containers based on a parts per million basis. I would strongly suggest that you continue to use the dehumidifier water, or deionized (distilled) water for watering your terrariums if you plan on keeping them. It will help immensely in keeping the level of soluble salts in the soil at lower levels. The kits are fairly accurate, btw.


  • tapla

    Kristi - I don't know if I'll get all the way through your posts or not. I have to do a bonsai demonstration for our club in a couple of hours, & I haven't even picked a tree yet. ;o) If I don't make it all the way through, I'll p/u where I left off.

    1) Your mix is so contrary to what all my local independent nurseries (I've asked at 3 different places) and even to what the folks at Four Winds recommend, I am needing some extra convincing. Maybe it's how I'm "wired" to really understand something well before proceeding.

    Well, I'm not being smart or speaking unkindly when I say that if you need additional convincing, I'm not apt to be twisting your arm very hard. You can trust what I say, or you can read through the 4 threads on this subject to get a feel for the hundreds of people that have taken away from my posts that long term aeration is key in container soils. If that's all you take with you, I'll be very happy & feel like I've accomplished something.

    I'll answer several of your questions by saying that it really doesn't matter what the soil is made of, as long as it holds the right amt of air and water & isn't phytotoxic. I choose ingredients for my soils that are the most durable (long-lasting) I can find, and that maximize water-holding ability while providing excellent aeration. I can tell you haven't read the entire post, because these questions are all answered in it.

    Both the bark-based soil and the gritty mix I often suggest will have close to 80% total porosity, with about 35% air porosity when the soil is fully saturated. That is the mark of an excellent soil.

    As far as the soils being organic - the bark soil has the same ingredients in them as bagged soils, and the gritty mix is just granite, Turface (baked clay) and bark. I consider these soils totally compatible with organic practices.

    As I scroll down through your posts, I'm realizing that it might take hours to type out all the answers, most of which are provided upthread. Many of the answers are overshadowed by your other concerns, and I have no feel for what questions are most important. You could help me out immensely if you ask a few of the most important questions & hold on until I answer them. Often, I'll be able to head off lots of other questions in my reply. I guess what I'm saying is "Let's organize our conversation." It will save me lots of effort & help insure that others will be able to follow & gain from it.

    Take care.


  • kristimama

    Hi Al,
    Thanks again, and I do apologize for blitzing you with questions. I see what you mean about your answers (if I had waited for them) may pre-answer some of my follow-up questions. You are always thorough and add so much value to this forum in everything you say.

    I assure you I have read this post, twice actually. And I've started onto the other posts you link to. But I admit it's a lot to take in and I'm still trying to absorb them all and apply it to my own specific situation.

    I think my questions are simply me trying to validate what I'm learning.

    I can certinly wait on your answers so that they can be organized in a way that everyone will benefit. Surely I'm not the only one to wonder about these things.

    Thanks! Have a good bonsai demo.

  • tapla

    Thanks, Kristi. I root-pruned/repotted 2 trees for the group - a black elderberry (lacy black foliage & looks much like a Japanese maple dissectum) and a pomegranate that came from your state (Roy Nagatoshi's nursery a little south of you). We had fun & the group was really lively & full of questions, but nothing like you. ;o) Lol

    Ok - I'm going to answer your most recent post now. If you still have questions, please just re-ask in manageable numbers & I promise I'll answer every question I'm capable of. Deal?

    In soils, there will be an inverse relationship between drainage/aeration and irrigation frequency. As intervals between the need to irrigate increase, it must follow that the soil must hold more water. To a large degree, this means that the soil particles must become smaller to hold the extra water, which decreases aeration. I make no claims that the soils I grow in are the most convenient, though I believe they greatly simplify growing in containers. The price you pay for good drainage and aeration is more frequent watering. Only you can decide if it's worth it to you.

    There is a price to be paid for the convenience of not having to water for extended intervals and it comes in the form of decreased root vitality. You will have to balance the vitality/convenience equation as you think best. The soils I make for myself and suggest here are designed to retain very little perched water so that root vitality (and thus plant vitality) can be maximized. It is impossible to maximize root vitality in any soil that supports perched water. To be sure, you can grow healthy/happy plants in some soils that support perched water, but you cannot achieve maximum vitality. Saturated soil kills roots and it kills them quickly.

    There is nothing that says these soils WILL need watering daily. That is still a function of plant mass, container size, and a whole host of other cultural effects. If you can't water daily, and your plants need water daily, unless you can solve the problem, it does little good to consider growing in a soil that cannot keep your plants hydrated, but there are some things you can do to boost the water-holding ability of your soils and still maintain a high degree of aeration.

    You refer to theoretical improvements, but there really isn't much theory involved in what I'm setting down here. The physical science in what I'm saying is pretty absolute, and my many years of practical experience along with the affirmation from many other forum participants also serves to move what I'm saying from the theoretical to the proven column. The real test comes in how you apply/adapt anything you learn here to your particular application - or how you don't apply it, as you choose; but, at least you should have a better understanding of the cause/effect of the relationship between drainage/aeration and a soils ability to hold water and how it affects your plantings.

    It's really difficult for me to gauge what I would do with your leftover bags of soil. My intuition tells me that you could probably treat it almost like the peat component of the 5:1:1 mix at the top of the thread. Why don't you try mixing 5 parts of bark, 2 parts of your soil, and 1 part of perlite and tell me what you think?

    I have a dear friend I visit with frequently who lives in Fremont (near you, I believe) and grows all her many citrus & other trees in a variation of the bark/Turface/granite mix. I believe she uses 2/3 Turface and 1/3 composted redwood bark, She is much happier after having made the switch in comparison to before, growing in prepared potting soil. I KNOW she often goes many days between waterings, so it's not going to be too difficult to build a soil to suit you and your trees - if you wish.

    BTW - you can always arrange for a phone conversation where I can answer all your questions as they arise (hopefully) ;o) and go into more detail. Let me know.

    Take care.


  • jodik_gw

    I'm very interested in what Al will have to say about the bark issue, and more to the point, what he thinks about using cedar.

    As a veteran dog breeder, I keep any and all cedar products, including bedding, mulch or anything else made from cedar as far away from my property as possible. There is a naturally occurring chemical in cedar that can damage the kidneys and other internal organs of animals, the same chemical that repels insects I would think, and I take no risks when it comes to the health of my dogs. I couldn't tell you the name of the chemical found in cedar, but I do know that cedar is not a good thing to have around if you own animals. We use aspen bedding, which is much healthier and a lot less dusty than other bedding, including pine.

    If you don't have animals or young children, it's not so much an issue... but if you do, be aware that cedar is damaging to internal organs! (I would guess that's why hamsters and gerbils don't live very long when bedded with cedar...)

  • kristimama

    Hi Al,
    So I suppose it's good that you didn't answer all my questions because it sent me on a seek and find mission. I've pored over the old listings, had a bunch of "a-ha" moments, and found the answers to a lot of my questions and concerns.

    But I'm hoping you can answer me these two...

    Terra Cotta vs. Plastic:
    In one post I think you answered you have a slight preference for terra cotta, and that it offers more margin of error for overwatering. But do you adjust the mix based on which kind of pot you're using, or is it irrelevant.

    Drip Irrigation
    Saw some sort of debate about whether your mix is compatible with drip irrigation systems. Will I be able to put all these pots with your soil on drip?

    It's surprising that my local nurseries (even the "good" ones) say to use commercially available potting mixes when they so clearly fail. I guess it's just a prevalent paradigm... but I'm not going to debate it with them. I've had all the convincing I need here on your posts and I'm almost ready to mix.

    Thanks again!

  • kristimama

    Hi again,
    Can you please say something about the relative longevity of your two mixes (i.e. Peat/Bark/Perlite vs. Turface/Bark/Granite).

    Can you put a "life span" (so to speak) on the mixes?

    You have said that commercial mixes might only last a single growing season before the roots rot.

    Whereas your Peat/Wood/Perlite will last longer, but "how much longer?" she asks.

    And then you have said that your Turface/Bark/Granite mix can last "almost indefinitely." Does that really mean never having to refresh the soil and repot?

    thanks for your ongoing lessons. ;-)


  • tapla

    Hi, Jodi. I must have missed your post somehow - I'm sorry. :o(

    "Cedar" covers lots of territory. I can think of at least 6 different genera of trees besides Cedrus, claiming the common name 'cedar'. I know that most are rich in bio-compounds that are a product of metabolism and repel insects, but I have never used any bark from a tree with even the common name "cedar". Sorry, but I can't comment on toxicity issues w/o going & researching it. Can I invite you to look into it & come back & share? ;o)

    In one post I think you answered you have a slight preference for terra cotta, and that it offers more margin of error for over-watering. But do you adjust the mix based on which kind of pot you're using, or is it irrelevant.

    The benefit of using a container with gas-permeable sides is to allow additional gas exchange in the soil, and to increase evaporation so that air returns to the soil more quickly. A side benefit comes in the form of cooler root temps due to the evaporative effect. Though you may wish to tweak a soil to help you get through from watering to watering, you shouldn't increase water retention so much that the benefits are lost & it ends up being much the same as growing in a plastic or glazed container.

    Read more here and more here, too

    ... saw some sort of debate about whether your mix is compatible with drip irrigation systems. Will I be able to put all these pots with your soil on drip?

    I suppose that's kind of hard to answer, because I don't know what you intend to do with the recipe, or which you'll use. I think they should be fine if delivery is via a mist emitter or if delivery is slow so water gets a chance to disperse by diffusion, rather than run through the container because the rate was too high.

    It's surprising that my local nurseries (even the "good" ones) say to use commercially available potting mixes when they so clearly fail. I guess it's just a prevalent paradigm... but I'm not going to debate it with them.

    Well, I can tell you that not every person working at nurseries and greenhouses is well informed. Some are, some are not. Often, the help is seasonal, unless you get to the key people. A parallel: You wouldn't believe it if I told of the conversation I had with a "lawn maintenance expert" this AM, who was bidding on the lawn care (not the mowing) at my business. He was the owner of the (his) business, but his lack of expertise was really astounding.

    Can you please say something about the relative longevity of your two mixes (i.e. Peat/Bark/Perlite vs. Turface/Bark/Granite). Can you put a "life span" (so to speak) on the mixes?

    You can tell, I'm really a believer & a stickler about aeration. I don't reuse my soils, but I have grown lots of plant material in the 5:1:1 mix for two, and sometimes 3 years when I get lazy. It hasn't been a problem when the plant/soil/container are all together for the duration, because the root mass actually becomes part of the soil structure and helps provide aeration, even as the soil itself is decomposing. The problem comes when you remove the plant material and try to reuse a collapsing soil. Eg: How much perlite does it take to make pudding drain well? ;o)

    So, I would MAYBE reuse the 5:1:1 mix once. The gritty mix will last for far longer than 'most any plant/soil combination should remain in the same container (because it's getting root bound).

    You have said that commercial mixes might only last a single growing season before the roots rot.

    Not quite. I don't usually speak in absolutes about that sort of thing. I think I probably said that peat-based soils will see considerable collapse before the end of a single growing season. If you were lucky enough that roots were somehow able to colonize the entire container, the effect would likely be fairly minimal. If the soil held too much water, or your irrigation habits were less than ideal - erring on the heavy-handed side, roots may not have been able to grow into the lower parts of the container, in which case the loss in plant vitality could be considerable, even to the point of killing the plant as a result of rotted roots.

    ... your Peat/Wood/Perlite will last longer, but "how much longer?" she asks.

    You've already seen that most peat mixes are in danger of collapsing within the period of a single growth cycle. Since bark is stable for about 4 times as long as peat, and that increases as the particle size increases, it's probably fair to say that the bark soil will outlast the peat soil several times over. The real question can't be answered because your idea about when a soil is no longer serviceable is probably much different than mine.

    And then you have said that your Turface/Bark/Granite mix can last "almost indefinitely." Does that really mean never having to refresh the soil and repot?

    No. Unlike some plants (like many houseplants) that will require repotting simply because the peat-based soil they're in has collapsed, the gritty mix will remain serviceable for several years. With this soil, the need to repot and root-prune will come as a result of the degree to which the plant is root-bound, rather than because of soil collapse.


  • kristimama

    Thanks Al.

    OK, so I think my strategy (since I'm essentially lazy LOL) will be to use the gritty Turface/wood chip mix and pot in terra cotta pots that are about 4" diameter larger than what they are now. My hope is that I can maximize the amount of time before having to repot. ;-)

    What I don't understand yet is whether the Turface Gritty Mix has a greater requirement for fertilizing than the Peat/Wood/Perlite mix.

    So the fertilizer post is my next destination, after the kids go to sleep. I expect more questions once I get there. ;-)

    Sheesh, I wonder if anyone has ever explained how all those orangeries in France have lasted these hundreds of years. Maybe there was an Al Tapla back then?

  • chills71

    Ok, where to begin.

    First off, Talpa, do you ever take a vacation away from home? I'm installing drip irrigation around the yard because I lose at least a plant a year to neglect when I'm away over the summer. A fast draining, non-retaining mix would only increase the mulch pile upon my return.

    Ok, maybe not the biggest concern...

    I like what i've read, enough that I will try to pot up at least a couple of my containers using a mix more like what you are describing. At the very least I will be adding wicks to a couple of my larger pots in an effort to increase the usable soil for those plants.

    Have you ever heard of a plant which doesn't like the mix you use?


  • tapla

    I vacation with some trepidation at having someone in to water things. I always return to find that a few plants missed their drinks & have suffered for it.

    I never claimed the soils I use can fix everything. ;o) You can't have it both ways, expecting to have looonng intermissions between irrigations and maximize vitality too. (no snotty tone here - smiling as I exhibit my keen grasp of whatever seems obvious) ;o) The soils I make for myself are designed to have very little or no perched water and to maximize water-holding ability within durable particulates when possible, while offering some adjustment in the volume of water held by varying only an ingredient or two.

    Have you ever heard of a plant which doesn't like the mix you use?

    I'm not really selling anything like "My Mix". If you read through the thread, you can see that I genuinely WANT to help people learn about soils and their effect on plant physiology. I have many years of experience growing in these mixes and I've never seen a plant that didn't grow very well in them when I tend to business. 'Lazy and inattention' are my biggest enemies when it comes to any plant mortalities. I can honestly say though, that they are very few.

    If any plant is known to do poorly in a well-aerated mix, you should avoid those I use, but if you cannot show where a plant DOES do poorly in that type of mix, any problems with vitality should almost certainly be attributed to grower error or general inexperience. Except for having to water and fertilize more frequently, soils like I suggest take a great degree of the worry and guesswork out of container culture. These soils really are a very good point from which to start or restart growing endeavors, but as always, the ball remains in the reader's court. ;o)

    Still waiting on the answer to the Turface question you posed in the Fig forum. I e-mailed 2 bonsai buddies from the DET area & I'm sure one will reply yet tonight. I'll let you know.

    Cheers, Chills.


  • chills71

    Thanks Al. (for locating the Turface, though I think I found a closer source)

    I am sold on the wick idea (I'll try it in a couple containers this spring).

    I bring my figs inside over the winter. When doing so one wants the plant to dry without overdrying. I've got the watering down pretty well now, but I worry that wicking out all the water will make giving the plants sufficient water for dormancy difficult (I guess I'm wondering if the plants are using that level of trapped water) Is my concern incorrect on some level?


  • tapla

    You're welcome. I sent a follow up in your mail, too.

    Inside - as in the garage or outbuilding - right?

    Yes, they use water from the container via capillary action and diffusion. Throw a few handfuls of snow on them from time to time. I "watered" my trees over-wintering in the garage 3 times during the winter.

    Take care.


  • lou_spicewood_tx

    Hi Al,

    I've noticed interesting thing about the fabric bag by Root Control is that the whole bag acts as wick so your mix seemed to dry out pretty fast compared to ordinary plastic container!

    I have a couple with heavy mix growing in the root control bag and they seem to do fine but it's hard to water though. The water just flows off the top to the side where the water comes out. I thought it was interesting thing with the fabric bag.

  • tapla

    You're using a cultural technique that invites drying of the soil periphery and you're surprised that it's drying quickly? ;o)

    In seriousness now - many organic soil components become hydrophobic when moisture levels drop below certain levels. For conifer bark and peat, that level is approximately 30%. 'Coco-wet' or 'Agri-2' wetting agents would go a long way toward alleviating the problem if it's something you cant/don't want to live with.


  • wormgirl_8a_WA

    Hi Al, I have read the entire 4 threads with much interest. Unfortunately, I only really got to the discussion of lime vs. gypsum AFTER I made up a batch of basic mix containing dolomite lime.

    Your older recommendation was to use sulfur to lower ph for acid-lovers, but it seems your newer advice is to avoid the lime and use gypsum when you want the ph on the acid side of 7.

    So I have three questions:

    1. Am I correct in assuming your updated advice is to use the gypsum and supplemental Mg for acid lovers, rather than the lime/sulfur combo? If so, is it a huge difference or just a minor one?

    2. What effect does powdered eggshells have on the ph? I have always used that instead of lime for my worm bin, and it does seem to raise the ph. But I wondered -- because your succulent mix called for "gypsum or eggshells."

    3. Any specific mix ratios you might recommend for strawberries and/or blueberries would be appreciated. I'm thinking you'd probably recommend your "gritty mix" for the blueberries?

    Thanks very much!

    Jenn aka wormgirl

  • tapla

    Elemental S will help lower pH in containers somewhat over the long term, but I usually don't recommend it for that purpose because it's so slow.

    1) Media pH is important, but less so than soil solution pH, but I still try to keep media pH south of 6.5. Since the gritty mix I use has a pH around 6.2-6.5 before amending, I feel that the gypsum is a better choice as a source of Ca because it doesn't affect soil pH to any significant degree, unlike dolomite. In the 5:1:1 soil, which has a considerably lower pH before liming (5-5.5), I usually prefer to add the dolomite, but if I was growing blueberries, I'd use the gypsum.

    2) You must be going WAY back. ;o) I don't remember suggesting eggshells, but I'm sure I might have, depending on the context of the conversation. Eggshells do raise pH, but not significantly because they break down very slowly. The main ingredient in eggshells is calcium carbonate (chalk, limestone, etc.) The shell itself is almost all (about 95%) CaCO3. The remaining 5% includes proteins and some calcium phosphate and magnesium carbonate. So, if you choose to use eggshells, you'll need to supplement the Mg, or make sure it's included somehow.

    3) Yes, I would grow them in the gritty mix. 2:1:1, 2:1:2, and 1:1:1 fertilizers are good choices for blueberries. You should prolly avoid using nitrate forms of nitrogen and chloride forms of potassium. The nitrate and chloride can be toxic to blueberries.


  • wormgirl_8a_WA

    Thanks so much, Al. I have a couple follow-up questions:

    1. You mention media pH and soil solution pH. If you have explained the difference upthread, I apologize for missing it. I'm supposing it has to do with testing pH dry vs. wet. In practical application, what do I need to know about this?

    2. When you use eggshells, do you merely crush them or actually powder them in the blender? When used as a fine powder, I'm fairly sure it has a pretty dramatic effect on my worm bin's pH (that's what I'm using it for, after all!) If one were to merely hand-crush the eggshells, though, I could see that having little effect on the pH (as a matter of fact, I found this ineffective in the worm bin). Then again, it would probably release a lot less Ca into the soil at one time. So the question is: how would you crush the eggshells, and about how much would you use?

    3. Gypsum is not carried at my local Home Depot, Lowes, or my favorite garden center. Before I look more, I thought I'd ask about the best place to find it. Would they carry it at the feed store?

    Thanks again, Al. I think I remember your advice from years ago when I used to frequent this forum. I only wish I'd known about your mixes back then!


    PS: I DID find "Soil Pep," composted fir and pine bark, at the local Home Depot - for those of you seeking pine fines.

  • tapla

    Hi, Wormgirl. I remember you from when you were here a long time ago. ;o)

    1) There is a lot to understand about pH in containers and how your irrigation water hardness and alkalinity, as well as its buffering capacity and the buffering capacity of the media affect the o/a picture, but I'll try to give an overview w/o getting into that area, most of which isn't too important to us anyway.

    Media pH is a measure of the o/a concentration of H ions in dry media. Media pH impacts pH of the media solution which, like nutrients, would be subject to rapid change if not for the buffering effect (CEC) of solid components in the media. So the importance of media pH to plants is not only its effect on ease/difficulty of nutrient uptake but more importantly, the availability of nutrients for diffusion/dissolution into the media solution.

    In short, media pH determines which nutrients might be available at a favorable media solution pH, and the media solution pH determines a plants ability to take them up in that solution. Since we are usually providing nutrients in a fertilizer solution that is designed to deliver nutrients at favorable pH levels, the media pH becomes less important than the media solution pH.

    2) Just as particulate size affects the delivery rate of nutrients like sulfur and dolomite, it would affects that of eggshells. Why not leave them lightly crushed and use them as part of the soil structure. You could probably use as many as you wish. If you powder them, I suppose I would use them at a rate of 1 tbsp/gallon of soil & double that if they are crushed to a fineness similar to kosher salt.

    3) I'm surprised you can't find gypsum. Feed stores will probably carry it - hardwares that sell fertilizer, too. I just saw it at an Acco Hdwe, if you have those near you. Do you have OSH's there? They would have it. As a last resort, Espoma makes it & bags it in either 5 or 10 lbs (I forget), but it's as much as 50 lbs at the other places & there's no difference - their lime is like that, too.

    Hey! The 'Soil Pep' sounds like a really good find!

    . . . promise you'll take care? ;o)


  • wormgirl_8a_WA

    Thanks, Al, for that explanation of media pH vs. soil solution pH. Believe it or not, I actually truly understand the sentence about the concentration of H ions in dry material - we were just learning about that last night in physiology class! Sometimes info comes to you just at the right time... anyway, the way you explained it is very helpful.

    I did find gypsum at Lowe's, they just didn't bother putting it on their website. Do you use the same proportion as for dolomite lime?

    I am frustrated trying to source ingredients for the gritty mix. First, bark. The size difference between "fine" and "medium" bark seems enormous. The finest medium bark I found is screened through 3/4" screen. I found "mini nuggets," but the type of wood was unspecified.

    Secondly, I bought Turface at my local John Deere Landscaping, and that seemed easy -- until I realized I'd come home with what must be an older product called Turface "All Sport." They do not list this product on their website, so I don't know how it compares to the MVP in particle size. I called the manufacturer to ask, but was only able to leave a message. Hopefully they either call me back, or someone here will be familiar with the older product. I'm pretty sure I can scare up some MVP here in town, but I wonder if I can use what I have.

    Thirdly, everyone around here carries chicken and pidgeon grit, but not turkey. All grits I've seen so far also have either oyster shells and/or additives. I have looked at crushed rock (too big) and sand (too small). I found pumice, but I was actually hoping for something heavier, and available in bags (it only comes in bulk). I have found Gardener Bloome "Horticultural Sand" which seems PERFECT, except it only comes in tiny, houseplant-sized bags. I have access to all the free pea gravel I want, but that's a bit big. Maybe I should go investigate the pool sand, but it sounds expensive.

    I expect my blueberries to be delivered at the end of this week and hope to pot them Friday. I will probably find good resources for these materials eventually, but at the moment, I'm trying to figure out what my best gritty mix options are. Tempted to try 1/2 bark and 1/2 turface, since they love it both acid and moist. I am also wondering about a little peat for the acidity. If anyone has opinions on my best options, I'd love your input!


  • tapla

    Do you use the same amount of gypsum as dolomitic (garden) lime?

    Yes - use a tbsp/gallon or 1/3 - 1/2 cup per cu ft.

    I am frustrated trying to source ingredients for the gritty mix. First, bark. The size difference between "fine" and "medium" bark seems enormous. The finest medium bark I found is screened through 3/4" screen. I found "mini nuggets," but the type of wood was unspecified.

    The same bark goes into the gritty mix as goes into the 5:1:1 soil. What happened to the 'Soil Pep' you found? You don't think you can use it?

    You should also be able to find fir bark there. Shasta Forest Products is in northern CA and they're a really big producer of bark. That's what I use in my gritty mix - screened fir bark. I buy it in 4 cu ft bags and last time I paid about $100 for 6 bags.

    If you let me know what major city you're in/near, I'll see if I can get in touch with bonsai friends/contacts near you & see what I can chase down. Those wheels sometimes turn slower than I'd like, so a little patience might be required.

    I've never used or seen Allsport before, so I can't really advise you. Can you describe the particle size? If you have access to a product called "Play Ball", you may wish to consider that instead of Turface. It's calcined diatomaceous earth and is actually superior to Turface in several ways.

    Silica sand in the 1/16" size wouldn't be too hard to find, or too expensive, as a replacement for granite. Anywhere that sells swimming pool supplies, or a masonry supply store (not big box) will have coarse silica. I paid $8 for the last bag.

    If you do the bark/Turface Allsport mix, I would use 2 Turface:1 bark. If you find the mix stays too wet, wick it until the planting matures & water retention becomes desirable, rather than a hindrance.

    Take care, Jenn.


  • wormgirl_8a_WA

    Hi Al - thanks, I emailed you regarding bonsai supply. I guess I thought I wanted *larger* chunks for the gritty mix. Perhaps I have the wrong idea there? Some of the fir bark you show in the pictures seems slightly larger. I'd love to just use my "Soil Pep," since I already have plenty.

    I just broke open the Turface "All Sport" and my hope is that it's the old name for MVP, or an older, similar product. It's particles range from about 1/16th" to 1/8th", with a few larger. It does not look like the "more uniform, smaller" particles in the product meant for slides. If I'm lucky the mfg. will call me back to let me know for sure, but it seems like the right stuff. I only got one bag - I will look for the actual MVP next time.

    I feel much encouraged already, Al. I will either make it to a masonry supply or swimming pool supply before planting time, or I'll just go 2/3rds Turface. Thanks for helping me formulate my plan! I WILL take care, and you do too, Al.


    PS: I think this thread is pretty near 150 replies - just a heads-up.

  • wormgirl_8a_WA

    Just got a call from the manufacturer. Turface All-Sport is the exact same product as Turface MVP - it's just packaged as All-Sport by John Deere Landscaping.

    I think it's the only type John Deere carries, because they didn't ask what type I wanted. I paid just under $10 a 50lb bag. I put the store locator link below.


  • justaguy2

    That's good to know, Jenn. A lot of people (myself included) initially struggled trying to find a source for Turface MVP. Knowing that John Deer carries it under a little different name should help many people out.

  • chills71

    John Deer near me would have to special order Turface, but they have something called Pro Choice Soil Conditioner (in red). Al, ever seen/used this stuff before?

    I picked up Espoma Soil Conditioner, but the Pro Choice stuff is about the same price for twice as much.


  • justaguy2

    Does the stuff from John Deer look the same as the Espoma Soil Conditioner (not counting color)?

    What you want looks like this (not counting color)


    It also doesn't hurt to soak a cup or so worth in water overnight to ensure it doesn't turn to mushy clay. If it is roughly the particle size in the pic and doesn't get mushy when saturated, it's good to go.

  • tapla

    Hey guys - could I have the 150th post so I can leave a link to the next thread after I get it up and running? I'd really appreciate it. Please don't answer. ;o)


  • tapla

    I didn't mean to cut you guys off. I had hoped I might catch the end of the thread at a more convenient point. Can I invite you to continue the discussion on the new thread?


  • tapla

    See immediately above for a continuation of this thread.


  • just_learning_grower

    Hi all, not sure I'd classify myself as a "grower" but I do dabble with my blue spruce. I have maybe a thousand I've grown from seed, ranging in size from 3" to 12" now, and still in 5" plugs.

    This fall I will transplant about 250 of the largest to 1 gal. pots and see how it goes (and move to 2 gal. next year, once I see how things develop.

    I've been researching soil-less container soils. I can buy Pro-Mix or the Sunshine Mix #4 but am concerned that the pH will be a bit high. I understand that in order for a blue spruce to be "blue" (at least for the 50% that have the ability to turn blue from the regular kaibab variety - although I have many "Majestica" that claim 90% will turn blue, and have some (claimed to be) "Misty Blue" which apparently were selected from the best of the Majestica orchard, but are no longer harvested) the pH should be about 5.5 or even less. I think both of the above pre-mixes have pH's greater than this.

    One mix I saw called for about 20% perlite, 20% vermiculite, 60% sphagnum peat moss, and 1/2 cup each of bone meal, blood meal, and dolomitic lime per 8 gallons of mix. I suspect that if I were to use this mix for blue spruce, I might eliminate vermiculite and reduce the lime to maybe 2 tablespoons? It looks from this thread that using primarily pine bark fines may be adviseable? I suppose I could also substitute turface for perlite although not sure I could find same. I don't know if I'd need any other additives like CRF? I'm hoping to keep costs down. It seems to me that I can mix my own soil for about 1/3rd less cost than pre-mix, unless I'm missing something? I have hundreds++ more blue spruce coming down the pipeline, so cost is important.

    Sorry for being so new at this. It was enjoyable planting the seeds (all outdoors, which was a challenge) but now a few years later I want to keep going with this, so am on to the potting stage. Any advise is helpful.

  • tapla

    Personally, I wouldn't consider the "20% perlite, 20% vermiculite, 60% sphagnum peat moss, and 1/2 cup each of bone meal, blood meal, and dolomitic lime per 8 gallons of mix" you mentioned. Even if you DO decide to use it, I can tell you that the .5 cup of blood meal suggested is enough to (by itself) supply maximum nitrification to more than 3.4 cu ft of soil (25.5 gallons). The bone meal breaks down so slowly in containers that it is very ineffectual as a Ca/P source as well.

    You should be able to use the 5:1:1 mix and add gypsum instead of lime to keep pH down to Alternate (and a good choice if you want to spend the money): Instead of the extra potash in the soil, you could use Dyna-Gro's 'ProTeKt' 0-0-3, which also provides silicon, which is particularly beneficial in container culture.

    I was contacted by a grower in PA last year about a soil/fertilizer program for Black Hills spruce, and the above is what I suggested. He was very happy with the results.

    Take care.


  • just_learning_grower


    Thanks for all of the above. I'll see if I can find pine bark fines. So far our horticultural wholesaler said they didn't have it. Someone told me just to use wood chips, i.e. in our municipality they retain the wood chips from the trees taken out, for use as compost (I've asked them if they have Black Walnut mixed in, which I think is toxic), as it's free. In any case, I'll look for the pine bark fines, and my question is - what does the potash do, is it to add nitrogen or potassium? And will I need the micronutrient powder after all of this, or does the Miracle Gro and/or other additives indicated cover for both SRF and micronutrients? Thanks, I need to get it right on this batch of blue spruce, and as mentioned want to keep costs down, as I have a over a thousand outgrowing their plugs.

  • tapla

    It would help those responding to your posts if you included where you live in Canada so we can have at least some idea of your weather patterns. In this case, it might offer a hint about what types of bark might be available in your neighborhood. I'm not sure if Can. has zones like the USDA zones, but if you know your equivalent USDA zone, it would be helpful stuff, too. BTW - what street is Canada on? ;o)

    Wood chips are not what you need for containers. If they were fine enough to be useful from the physical perspective, they will break down too quickly and tie up nitrogen. When using a wood product, stick with conifer bark only. I have used pine, hemlock, and fir, and found them roughly equal in performance.

    Potash supplies potassium (the 'K' portion of NPK). Since your trees will use about 3/5 as much K as N, the 3:1:1 ratio fertilizer will be somewhat deficient in it's ability to meet the plant's K needs. Other than that, the fertilizer is a very good choice. It doesn't supply Ca and Mg, but you won't need a micronutrient supplement if you follow the outline I offered - they're covered, along with the sulfur that is missing from the MG 30-10-10.

    There is also no need for a CRF if you're diligent about fertilizing.


  • just_learning_grower

    Al, this is very helpful.

    My "street" in Canada is Ontario, actually a small town near Sarnia (about 30 minutes east of Port Huron, Michigan). I think we're zone 6(a) but I understand that many plants/trees rated for zone 6 tend to "expire" fairly quickly. We don't have alot of conifers in our area, naturally growing - we tend to be more the hardwoods. I'm still striking out on locating bark chips (got another email back this a.m.) but I think there may be a mill north of us (if it still exists) so I'm going to check there.

    Hoping we can keep up our dialogue, it's quite interesting and very helpful.

  • oscar08

    A big thanks for this article. Pearched Water Table and conditions that give rise to it were something I knew nothing about and it sure explains the problems I've been facing. Thank you so much!

  • tapla

    JLG - the dialog depends on you. ;o) I'm around almost every day & try to answer any questions that are addressed to me whenever I can. That you find the info & dialog interesting and helpful is pretty much my reason for being here, so I'm very pleased that you say so. Thank you.

    Oscar - you're so very welcome. I always hope that people reading the OP at least keep the info in the back of their minds - even if they don't embrace the concept in practical application. It, for those folks, can still be a helpful diagnostic aid if ever things go awry. Your post stands as testimony to that fact. Thank you.


  • naplesgardener

    Question for Al:
    It was hard for me to find park bark fines but I found some an hour north of me. Now I have just a few bags left and am getting the jitters of "what do I do when they're gone".
    Here in Florida we have shredded eucalyptus mulch which I use (as mulch) because it breaks down much slower than other mulches.

    Do you think it could replace pine bark fines in the mix?
    I guess I could try an experiment and plant the same plant in the two mixes to compare.

    Just wanted to ask your opinion. I have heard that cypress mulch inhibits growth so I won't use that.



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