jdwhitaker_gw

Container soils and water in containers III

jdwhitaker
13 years ago

We've worn out two threads in less that two years since Al's original post. Let's keep the discussion going...

CONTAINER SOILS AND WATER IN CONTAINERS

Posted by tapla z5b-6a MI (My Page) on Sat, Mar 19, 05 at 15:57

The following is very long & will be too boring for some to wade through. Two years ago, some of my posts got people curious & they started to e-mail me about soil problems. The "Water Movement" article is an answer I gave in an e-mail. I saved it and adapted it for my bonsai club newsletter & it was subsequently picked up & used by a number of other clubs. I now give talks on container soils and the physics of water movement in containers to area clubs.

I think, as container gardeners, our first priority is to insure aeration for the life of the soil. Since aeration and drainage are inversely linked to soil particle size, it makes good sense to try to find a soil component with particles larger than peat and that will retain its structure for extended periods. Pine bark fits the bill nicely.

The following 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 soil available for root colonization. A wick will remove the saturated layer of soil. It works in reverse of the self-watering pots widely being discussed on this forum now. I have no experience with these growing containers, but understand the principle well.

There are potential problems with wick watering that can be alleviated with certain steps. Watch for yellowing leaves with these pots. If they begin to occur, you need to flush the soil well. It is the first sign of chloride damage.

One of the reasons I posted this is because of the number of soil questions I'm getting in my mail. It will be a convenient source for me to link to. I will soon be in the middle of repotting season & my time here will be reduced, unfortunately, for me. I really enjoy all the friends I've made on these forums. ;o)

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

Water Movement in Soils

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 to sustain plant systems. Gas Exchange - It must be sufficiently porous to allow air to the root system. 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 movement 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 pot than it is for water at the bottom of the pot. 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, waters 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 is, in every pot, what is called a "perched water table" (PWT). This is water that occupies a layer of soil that is always saturated & will not drain at the bottom of the pot. 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 equal the GFP; therefore, the water does not drain, it is "perched". 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 is the area of the pot where roots seldom penetrate & where root problems begin due to a lack of aeration. From this we can draw the conclusion that: Tall growing containers are a superior choice over 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 be able to take in air at the roots in order to complete transpiration and photosynthesis.

A given volume of large soil particles have less overall surface area in comparison 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 PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. Large particles mixed with small particles will not improve drainage because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential. Water and air cannot occupy the same space at the same time. Contrary to what some hold to be true, sand does not improve drainage. Pumice (aka lava rock), or one of the hi-fired clay products like Turface are good additives which help promote drainage and porosity because of their irregular shape.

Now to the main point: When we use a coarse drainage layer under our soil, it does not improve drainage. It does 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 reduces available soil for roots to colonize, reduces total usable pot space, and limits potential for beneficial gas exchange. Containers with uniform soil particle size from top of container to bottom will yield better 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 in the soil for water to be attracted to than there is in the drainage layer.

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, insert a wick into the pot & allow it to extend from the PWT to several inches below the bottom of the pot. 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 rapidly break down to a soup-like consistency. 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 to death because they cannot obtain sufficient air at the root zone for the respiratory or photosynthetic processes.

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 several inches up into the drain hole . Take note of how much additional water drains. 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 PWT along with it.

Having applied these principles in the culture of my containerized plants, both indoors and out, for many years, the methodology I have adopted has shown to be effective and of great benefit to them. I use many amendments when building my soils, but the basic building process starts with screened bark and perlite. Peat usually plays a very minor role in my container soils because it breaks down rapidly and when it does, it impedes drainage.

My Soil

I'll give two recipes. I usually make big batches.

3 parts pine bark fines

1 part sphagnum peat (not reed or sedge peat)

1-2 parts perlite

garden lime

controlled release fertilizer

micro-nutrient powder (substitute: small amount of good, composted manure

Big batch:

3 cu ft pine bark fines (1 big bag)

5 gallons peat

5 gallons perlite

1 cup lime (you can add more to small portion if needed)

2 cups CRF

1/2 cup micro-nutrient powder or 1 gal composted manure

Small batch:

3 gallons pine bark

1/2 gallon peat

1/2 gallon perlite

handful lime (careful)

1/4 cup CRF

1 tsp micro-nutrient powder or a dash of manure ;o)

I have seen advice that some highly organic soils are productive for up to 5 years. I disagree. Even if you were to substitute fir bark for pine bark in this recipe (and this recipe will far outlast any peat based soil) you should only expect a maximum of 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 genetic potential. If a soil is desired that will retain structure for long periods, we need to look to inorganic amendments. Some examples are crushed granite, pea stone, coarse sand (no smaller than BB size in containers, please), Haydite, lava rock, Turface or Schultz soil conditioner.

I hope this starts a good exchange of ideas & opinions so we all can learn.

Al

Comments (150)

  • jdwhitaker
    Original Author
    13 years ago
    last modified: 5 years ago

    If anyone wants to do their houseplants a favor they should definitely try the granite:turface:bark mix. The difference it made for my indoor plants was amazing.

    I would also note that the faster draining mixes do require more frequent watering--but not as much as you might think. The superior root systems you get with increased aeration will help greatly with drought tolerance. I use coarse bark and very little peat in my outdoor mix, and never have problems with underwatered plants despite living in a hot & dry climate.

    Jason

    Best Answer
  • filix
    13 years ago
    last modified: 5 years ago

    Al earthworms are welcome in that raised bed mix right? I made my 2x10s. Is that deep enough? I put cardboard on the ground before I added the mix. is that ok? Thanks. Filix

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  • tapla
    13 years ago
    last modified: 5 years ago

    Sounds fine - worms & similar beneficial fauna are always welcome in raised beds - not so welcome in containers, though.

    On the depth question: Yes, 9-1/4 inch depth is plenty for almost anything.

    Al

  • filix
    13 years ago
    last modified: 5 years ago

    Thanks Al. How long will this soil hold up? You do have to add the C.R.F every year right. I think you said the second year the soil does even better. I did 4 parts composted pine bark, 1 turface 1 peat 1 sand 1 compost then some dolomite lime and I used the same C.R F. as I did in my containers. I did 4 parts pine bark because we had a week of rain and the stuff was very wet and hard to screen. I'm coming down the home stretch for all my hard work. And with your help, my plants are happy, and I have learned alot this year. Filix

  • filix
    13 years ago
    last modified: 5 years ago

    I have made a few mistakes whem I mixed the soil. Next year I will do things a little different. When I mixed the soil the pine bark was always damp or wet. The peat dry and hydrophobic. When I added water while mixing I noticed the peat would stay in small clumps that were dry inside. If I mixed with everthing dry as could be, then everything mixed better. But then you have to wet everything so some of the peat won't be dry half way down the pot. I'm mixing this with my hands having latex gloves on. Is there a way you can mix this dry as possible, fill your container, then water from the top and everything getting wet? I mixed in a wheelbarrow. Some of my batches were a little to wet I thing. Because when I put them in the container the soil seemed to pack rather tightly. And still is. Is there anyway to loose it up? They all have plants growing in them. Some of the soil in my containers has a crust on the top. Not sure why. Hope I'm not being too much of a pain with all my questions. filix

  • justaguy2
    13 years ago
    last modified: 5 years ago

    Filix,

    When I mixed mine (50% bark fines, 25% peat, 25% turface) I used 5 gallon buckets. 2 filled with bark, 1 with peat, 1 with turface.

    I then flooded each and let them sit to soak up water.

    Then I dumped them in a wheelbarrow.

    Then I added CRT and lime and mixed. I mixed with a shovel turning everything over as I made one revolution around the wheelbarrow. That was enough.

    Everything is well mixed, but I do see the small clump of peat here and there. Perhaps two revolutions around the wheelbarrow next time.

    The only problem I had was the first batches were hydrophobic. To solve this I allowed the media to sit longer in the buckets and when dumping from wheelbarrow to container there was excess water left.

    I am surprised that even whiskeybarrows require daily watering with this mix. I was thinking large containers wouldn't, but everything does from large to small.

    So far I am not impressed with it in self watering containers. I lost 6 peppers to dessication in 24 hours and this is in an earthbox covered with plastic mulch. I think if I top water long enough for roots to reach the bottom it will be fine, but next year I will use regular bags of store bought potting mix for the self waterers.

    For comparison I have a pumpkin in 2 self waters and these are doing fine, but they are planted almost to the bottom of the container and the peppers were in the top 2 inches.

  • tapla
    13 years ago
    last modified: 5 years ago

    Felix - I only added fertilizer as needed the first year. In subsequent years, I've added none, I'm in my 6th or 7th year with the soil in raised beds now. Last year I planted a stray parsley plug I had left over in a raised bed. It literally amazed me with how huge it grew. It had at least 3 times the mass of plugs planted in the garden (and my garden soil is excellent, as well).

    JaG, et al - I screen my peat through 1/4 inch hardware cloth to break up all the large pieces before I mix the soil (less than 5 minutes per 5 gallons). I then wet the bark down well (not soggy) before incorporating peat & perlite. Then, I mix with a spadefork in a wheelbarrow. I never have wetting problems. I mention often that the soil will need frequent watering, but I have planted several hundreds of containers (prolly several thousand over the years) & never lost a single plant to dessication. What's even a greater contrast to what you report, is that I usually remove 50% or more of the root mass of all the greenhouse material I use in containers, which should compromise their hydraulic capabilities, but I still have no problems with roots drying out as long as I water daily. Though I don't use self watering "earthbox" type containers, I do wick water a number of small containers, and these have not been problematic either.

    Al

  • filix
    13 years ago
    last modified: 5 years ago

    Al quick question for you. I planted my maid of orleans jasmine in that long term mix. 1 part bark 1 part turface amd 1 part sharp sand. I hope it was ok to put a handful of lime and a handful of CRF. because thats what I did. filix

  • tapla
    13 years ago
    last modified: 5 years ago

    I suppose it depends on what kind of liming material you used & to what volume of soil you added it to, eh? ;o)

    The soil mix you describe should be very near or slightly below neutral pH (7.0). The addition of dolomitic lime will probably raise pH to the plants upper preferred range (7.5) or even higher. If you have water high in carbonates, you could have some pH related nutrient deficiencies show up. If you used gypsum as a liming material, you'd probably be in better shape, but I would still use an acid-forming fertilizer in either case. Good watering habits (flush soil so about 10-15% of the total volume of water applied drains from the container bottom) will help keep carbonates from building in the soil.

    Good luck.

    Al

  • filix
    13 years ago
    last modified: 5 years ago

    Thankyou Al. We got the remains of that tropical storm. Alot of rain. I looked out my window and I noticed one container was filled with water and wouldn't drain. I thought that was strange. Then I remembered that I had a bag of fafards potting soil. So I thought I would just improve it a bit by adding some pine bark and some turface to it. The four containers that I put that mix in all did the same thing. Wouldn't drain right. My containers that I have going down the driveway all have Al's mix but one. For a test I filled one with fafards. Just for yucks. That one is draining fine. Did I screw up the balance of the fafards by adding stuff? filix

  • tapla
    13 years ago
    last modified: 5 years ago

    I'm lost, Felix.

    Al

  • filix
    13 years ago
    last modified: 5 years ago

    Sometimes I'm numer than a pounded thumb!:) Won't do that again. Al's mix is working just fine. I had a few pots and a few seedlings, but not enough bark fines. So I got cheap and tried to expand that bag. I can't belive I went through two truckloads of barkfines. My plants are doing great. Thanks many times! filix

  • filix
    13 years ago
    last modified: 5 years ago

    My experiment of putting farfeds potting soil in one pot, and Al's mix in the other is the plants in Al's mix are twice as big. Same size container, same plant, same location, watering, feeding. filix

  • Amanda
    13 years ago
    last modified: 5 years ago

    Hey, so I have a few questions which might just be common sense--but I'm pretty new to this and want to make sure I understand before I start making my own mix.

    1) Is there any particular reason for incorporating peat into the mix? Could I just use regular pine bark fines? (And if I understand correctly, not using the peat would mean I should use gypsum, not domolitic lime for adding Ca so that I don't inadvertantly cause the soil to become too alkaline?)

    2) Assuming that I want a standard mix for long-term container indoor and outdoor plants, as well as some veggies, this is the sort of mix I am imagining--could you critique it? :-) where exactly would the addition of worm castings to the intitial mix fit in? As a micronutrient supplier/time-release fertilizer? How much of my plant's required nutrient needs could be filled by the worm poo, since its rated 1-0-0 (even though I've heard that the rating is innacurate, and it is instead balanced)?

    3 parts pine bark fines
    1 part worm poo
    2 parts turface/granite CRF
    gypsum

    would 4:2 organic:nonorganic be too dense for the mixture? And so should I reduce the wormpoo or the pine bark?

    Thanks so much!

    Amanda

  • tapla
    13 years ago
    last modified: 5 years ago

    1) Peat is kind of optional, but I like how it tends to help keep pH on the south side of neutral. Whether or not I would use it also depends in part on the particulate size of the other ingredients. E.g., if the bark size is larger, like mini-nuggets instead of fines that are partially composted, I'd use peat mainly for the added water retention.

    If you don't use peat & are using a soil that is low in organic material, I would suggest gypsum as a Ca source unless you are growing plants that like a higher pH, so you are correct.

    2) Truthfully, I would skip the worm castings in container soils. They do add a little in the way of micronutrients, but nothing you couldn't easily accomplish chemically or organically with the addition of any one of a number of fertilizers or supplements that include the minors.

    I would usually not use Turface in soils that are intended for short term plantings like annual veggie crops or "pretty flowers". ;o) I Use Turface in soils for plantings I intend to be in the same soil for more than a growing season or for bonsai or plants in very shallow containers where drainage is critical. For long term plantings, I use a base soil of equal parts of uncomposted pine or fir bark, Turface, and crushed granite. I vary the amount of Turface/granite as needed to optimize the amount of water the soil holds. You may very well be able to eliminate the granite if you are in a hot or windy area. The equal parts mix is excellent for cacti, succulents, and houseplants in general. With only a couple of other amendments added, you can usually fine tune this mix to suit anything you'd like to grow. The mix you suggested is quite close to something I might use, except for the castings.

    Good luck, Amanda.

    Al

  • legacy
    13 years ago
    last modified: 5 years ago

    I don't see granite in the same class as perlite or that the use of perlite as an issue of economy. Commercial growers and professional and home gardeners use perlite for functionality: moisture retention, soil aeration, commercially used and well studied for its multi-functionality, easily accessible, consistency and durability, pH neutral, and light wt for storage, carrying, use, and transportation where unique individual benefits as well as insurance for solid building structural support for intense cultivation in small spaces may be of primary concerns.

    A soilless medium for containers serves only to provide efficient root uptake of air/water/nutrients and some structural support and anchor needed by a plant. The amount of root support is minimal, for an outdoor banana tree can be grown successfully with a light-weight potting mix consist mostly of perlite and some coir). The specific ingredients are not as important as a final mix that would allow the roots to function optimally in a range of these native preferences with a given light exposure and climate, because plants, like all living things, are adoptable to a range of seasonal and environmental changes.

    Mixing the right potting mix is simple and should be open to fine adjustments suitable for a micro-climate. If things don't work out, a good gardener can always amend and repot base on observable symptoms exhibited by a plant.

    There are many published successful soilless recipes in use commercially and privately. There simply is not one ideal soilless mix. There may be a basic mix with which to build upon to be successful but bear in mind that one-size-fits-all potting mix does not exist. Three major reasons are that horticulture requirements amongst plants, local growing conditions and climates (and growing method/planters used), and natural regional resources vary widely. Even within similar regions but different growing conditions, for example, turface and granite amendments may serve little horticultural or operational benefits than a simple higher percentage use of perlite for shady, greenhouse, and balcony gardens or nursery growers and female, young, and senior gardeners with large collection of planters where lifting Truface and granite and planters can be major gardening and maintenance obstacles, while these ingredients may serve ground level containers or raised beds in dry and windy climates and open growing conditions better. It's important to consider what is preferred or considered ideal by one gardener or in one growing condition may not be ideal or preferred for the next.

    The basic reason behind making one's own mix is the flexibility and hopefully the ultimate success such flexibility would enable a gardener in meeting first the horticultural needs of a plant with respect to a given local climate and any unique micro-climate and growing conditions and limitations along with personal economics and accessibility of an ingredient and any secondary personal preferences. Before one can identify the necessary ingredients of a good mix, one needs to know and MUST ASK what preferred air to moisture retention ratio, suitable pH range, and drainage preferences are needed and required by my plant to grow optimally, what unique limitations in my current growing conditions (light/wind/rain/cumulative wt. of planters and materials) are in meeting these native requiremnts, and then what specific functions does each amendment serves to provide for the needed conditions along with a gardener's personal preferences and objectives.

  • tapla
    13 years ago
    last modified: 5 years ago

    Interesting - thanks for the thoughts. You'll find everything you just said, above, and/or in a previous thread on the same topic, if you sift through the thread. ... nothing to disagree with.

    Al

  • Amanda
    13 years ago
    last modified: 5 years ago

    So supposing that one is using a mix in which water retention is not an issue, instead of using peat as what seems to be a soil ammendment to create a mildly acidic soil pH, could one theoretically use spent coffee grounds to the same effect (with its availability being greater, and its acidic properties)? Does anyone know exactly/generally how much coffee grounds change soil acidity per unit measure?

  • justaguy2
    13 years ago
    last modified: 5 years ago

    They really don't. Brewed coffee grounds aren't strongly acidic, but near neutral in pH. The acidity is in the coffee itself.

    The water and fertilizer you use will have a stronger affect on pH than the potting mix.

  • tapla
    13 years ago
    last modified: 5 years ago

    In addition, coffee grounds break down quickly, making them generally unsuitable for use in containers. They are also extremely hydrophobic (water repellent) when they dry down to below 30-35% moisture content.

    Al

  • legacy
    13 years ago
    last modified: 5 years ago

    It has been written that brewed coffee grounds is pH neutral as well as mildly acidic. I have not tested the actual pH myself or researched into it. I know for sure recycled coffee grounds can provide quick but safe usable nitrogen supply to containerized acid-loving gardenia with the pH controversy aside.

    A year or so ago when I was drinking coffee (just started recently again - might as well for my gardenias), I piled on (top dress) used coffee grounds DAILY on my container gardenias that also didn't get get acid-loving fertilizer. I did it for the pH reason initially to keep the potting mix acidic, and the spent coffee grounds turned any early yellowing foliage green virtually overnight. The acid-loving container gardenias seem to respond and thrive to the added coffee grounds noticeably either from the pH (whatever it is) or the nitrogen, including its quick-draining and texture which I know gardnias prefer. Any possible water-repelling texture or property of the coffee grounds seemed to be perfect for container gardenias and have made an ideal organic mulch for humidity-loving gardenias as well and without destroying the total porosity and making the potting mix sticky. These observations are not based on one acid-loving gardenia but three containers of the same variety - Veitchii.

    I recall I read somewhere a few days ago that gardenias are of the coffee family (interesting), but I didn't verify this fact or look into it. I wonder if we could grow gardenias successfully or easily in high percentage recycled coffee grounds?

  • legacy
    13 years ago
    last modified: 5 years ago

    With some precaution and maintenance, a gardener can also substitute peat for proven certified coir for higher water retention, better rewetability, and durability and stability (2-4x) with a pH of 5.5 to 6.8.

  • ecosse
    12 years ago
    last modified: 5 years ago

    Repot (its 110), wick it for now, or?

    Hi- Found this thread a week ago and its been bedtime reading since-all 400+ posts. Bless you, Al, you have the patience of a saint with us!

    Wish Id found it earlier- At the end of May, I lost a number of plants in my balcony container garden due to soil/ drainage issues. Especially painful was losing some mini roses. The leaves started browning from the outer edge, mummifying. A nurseryman told me then there was not enough water uptake available for any number of reasons (all in this thread!) and the heat exacerbates the issue.

    I bought a Peach Brandy Mini from him (well, hed given a free diagnosis ;-). Besides, it was sitting there in a one gallon growers container on a bed of gravel in full sun at 100 degrees and looked happy. (and was clearance priced). Was potted in what appeared to be about 70% coarse sand and 30% mulched wood products. Very fast draining.

    Tried to replicate the soil, (this before reading Als -taplas- article) ended up a mixture of a sand based succulent/palm mix, potting soil, pumice, and perlite, and repotted in a 12 inch pot, cached inside a 14 in pot lined with old newsprint (for insulation)

    2 weeks after, temps here were 118, on my (south facing) balcony about 120, and on this new one, about 50% of the leaves were doing the browning thing. Checked, and although the pot drained quickly, it was also holding a lot of moisture. Now, at 6 weeks, the browning has stabilized -tho still there-and there is a touch of new growth. If we can just make it through the summer

    So

    Should I repot (temps will be over 100 here til Sept, overnights in the 80s) using a modified (add pine bark -well, sifted orchid bark-and more pumice) version of Als recipe? Modification due to financial and availability constraints. (Pine bark here is available in sizes you could use in a fireplace, no wood chipper available, dont think my old food processor would survive ;))

    Wait for cooler weather, poke a wick up inside for now?

    In either case, fertilize? I have Osmocote and some liquid emulsion charmingly named "Fish and Poop". Seriously. Do NOT open indoors =0

    I noted in an earlier post, Al suggested using pumice as a cache-pot insulator. Can do. Hmm. Maybe vermiculite? Breathes, holds moisture- for evap. effect?

    Thanks! Special one to jdwhitaker for keeping thread alive-and hot/dry advice!

  • ecosse
    12 years ago
    last modified: 5 years ago

    Sorry-missed in the edit

    "using ***my soil in*** a modified (add pine bark -well, sifted orchid bark-and more pumice) version of Als recipe?"

  • tapla
    12 years ago
    last modified: 5 years ago

    I'm pretty confused, but you should add a wick if the soil isn't drying down after a day or two and you should NOT repot out of season, especially in that heat. Potting up would be ok, but there is a difference between repotting & potting up that you may not yet discern. Repotting entails root-work - potting up does not.

    Use anything in the cache pot that is not phytotoxic and that will breathe while holding good amounts of moisture. Cooler (than your ambient) root temperatures are required to insure good plant vitality.

    Try not wetting foliage when you water to help stop burned leaf margins and fertilize as required when the plant is actively growing. Most plants take a little siesta when temperatures get to the extremes you described & fertilizer is largely unnecessary during the quiescent period.

    Al

  • zeckron
    12 years ago
    last modified: 5 years ago

    Hey Al, excellent reading. Thanks for sharing all that you've learned through your years of personal research and experimentation. I've learned a lot reading through this whole thread (took a long time!).

    Do you ever lend your expertise to the folks in the cacti/succulent forum? I've been there everyday for the past month as I'm getting very interested in succulents, especially mesembs. I've been using Steven Hammer's suggested "mabel mix": two parts loam, one part coarse sand, one part pumice. I think most of the folks over there use this as well.

    Have you ever experimented with any cacti/succulent (especially the smaller mesembs) soil mixtures? If so, your experience would be most welcome.

    Thanks again for all the great info!

  • tapla
    12 years ago
    last modified: 5 years ago

    I'm no cacti/succulent expert, but I have quite a few - mainly succulents. I've settled on a mix of:

    6 parts screened Turface
    3 parts starter grit (crushed granite)
    1-2 parts uncomposted pine or fir bark (1/8-1/4" chunks)
    1 part coarse silica sand
    1 part vermiculite
    Micromax (micronutrient source)
    gypsum or egg shells

    This is an easy mix for me as I usually have several cu ft of bonsai soil mixed up/on hand & I just amend it with additional Turface and granite, then add in the silica, vermiculite, and a Ca source.

    Contact me off forum & I'll send you a small bag for your "evaluation". ;o) I'm pretty sure you'll really like it.

    Al

  • fly2cast
    12 years ago
    last modified: 5 years ago

    Let me offer a testimonial on how good the soil mixture listed on the top of this post has worked for me this summer. Previously I only used soil mixtures I bought at stores. This year I used Als soil mixture for about 30 containers all containing either geraniums or lobelia and hooked up to an automated drip watering system. My flowers are the fullest, nicest looking, biggest growing that I have ever grown. I cannot believe how large the plants are in such small containers that I have provided. I have several other plants that were kept in their original containers and also watered with the drip watering system. They not doing nearly as well. I cannot seem meet their watering demand (either they are too wet or too dry) because of the soil - it retains too much water.

    With Als soil mixture, the water drains immediately after watering but retains enough water to keep the roots moist until the next watering. If I had to recommend anything, it would be to use an automated water system with this soil mixture. In hot weather with small containers, it will dry fairly quickly.

  • ecosse
    12 years ago
    last modified: 5 years ago

    Al-

    Thanks for giving me the answers to my concerns! (Sorry I gave too much info)

    Much appreciated!

  • amyben
    12 years ago
    last modified: 5 years ago

    Hi again, how is everyone?

    Having carried all of the pine bark, 50lb. bags of turface, etc. up to our 3rd fl. roof and mixing it myself due to my younger, stronger, more athletic husband's hernia history, I am wondering what "legacy" means by "female".

    I would also like to say that my plants are doing swimmingly, without drowning of course, thanks to Al's mix, and Al and Dorie's wonderful advice.

    Thanks again and agian, Amy

  • tapla
    12 years ago
    last modified: 5 years ago

    Such kind words from (almost) everyone lately. Thanks to all for taking the time to tell of your findings and results. Thanks too, for the questions that keep the thread interesting & active. I've had lots o' fun & have made plenty of pals over the last few years at GW & particularly here on the Container Forum. You guys ROCK! ;o)

    Al

  • nyssaman
    12 years ago
    last modified: 5 years ago

    I tried brown dress shoe thin nylon laces cut in half the taped or glued end is pushed into the soil than I use something thin to push it in further - I find this only works for really waterlogged soils - If the soil is moist but not soaked it will not work - One pot I have that I just flushed yesterday has filled up half of a tupperware container and is still dripping - maybe there are more materials that wick better but the one pot started wicking right away as soon as I pushed it into the soil - I tried running shoe laces didn't work at all. I think this may have something to do with an already mature root mass at the bottom of the pot - if there is a substantial mass it doesn't seem to work for me.

    cheers

    Jeff

  • zeckron
    12 years ago
    last modified: 5 years ago

    Ran by my local nursery today to pick up some perlite and they actually had a new pallet of pine bark fines! Shocked the heck out of me since I had been calling them almost daily for the past week. On the phone they claimed to never stock the stuff and said they don't sell the stuff they use for their containers. But low and behold they got a fresh pallet in just today! Picked up 3 bags.

    Al, contacted you regarding evaluation bag. Thanks again for all the great info!

  • justadncr
    12 years ago
    last modified: 5 years ago

    Well I want to add my thanks to Al as my 100 pots are all doing wonderfully. I have never had this much success and have gardened for 30+ years. I do have drip irrigation but I dont think it is responsible for the success. The mix gets wet easily but dries out and doesnt seem to be waterlogged.

    I do have one question. I used part soil conditioner and part small bark chips for most things. Some bark chips are 1/2 to 3/4 in. I used more of the bigger ones in the long term planting. I have since read everything should be the same size?? Also I have only used bags of bark chips. Probably fir as I am in the PNW.

    None of it was composted.
    When do you need composted and how do you compost it?

  • tapla
    12 years ago
    last modified: 5 years ago

    ;o) Thank YOU too, for the kind words, E. I'm soo happy for you! From our conversations, you know I use some soils with a very high (often 100% or near that) % of inorganic ingredients. I usually ALWAYS use an uncomposted bark in these soils (fir or pine, depending on a couple of factors) because the intent of using such a high % of inorganic materials is soil longevity and resistance to collapse over a longer expected life. The key consideration is that there is such a small % of bark in the soil that N immobilization is generally never an issue.

    I prefer a composted bark product for all my short term plantings ("pretty flowers" and veggies, or stuff I'm just playing around with). The two reasons for that choice are economics and N immobilization. Less N is tied up in partially composted bark than in uncomposted, and in a soil where 3/4 or more is bark, that effect can be significant if not addressed. It's not a huge problem though (if you use an uncomposted conifer bark), as long as you're cognizant of the fact that you will be required to furnish the plant a diet higher in N to maintain best vitality.

    Take care - good to hear from you.

    Al

  • justadncr
    12 years ago
    last modified: 5 years ago

    Well i am glad I am on the right page. I thought I was then I read a little more and get confused.
    If one was to judge by the look of the plants in my containers i dont think I need to add or do anything else.

    I do wonder about my house plants. I use weak S.T.E.M. every time I water. Do I need to feed them with a NPP fertilizer once in a while?
    Thanks again for all your help.

  • tapla
    12 years ago
    last modified: 5 years ago

    Oh yes. STEM supplies primarily the minor elements in soluble form. You'll still need to supplement the macro-nutrients, (N)-Nitrogen, (P)-Phosphorous, (K)-Potassium, Magnesium, and Calcium. W/o looking, I think STEM contains adequate Sulfur. In general and for a high % of plant material, I would suggest MG 24-8-16 in a soil with a high organic content and something like a balanced fertilizer (20-20-20 eg) in a soil with a high mineral content (Turface, granite, pumice, etc).

    Al

  • wi-northernlight
    12 years ago
    last modified: 5 years ago

    CONFUSED !

    It appears that Al's recipes below are not the same for both batch sizes. The generic recipe is 3:1:1. The big batch seems to come out to about 4:1:1. The small batch looks like about 6:1:1. Which is it? or doesn't it really matter? or am I totally in error?

    Thanks to all,

    Bob Nlight


    PREVIOUS POST WITH AL'S RECIPE

    My Soil

    I'll give two recipes. I usually make big batches.

    3 parts pine bark fines
    1 part sphagnum peat (not reed or sedge peat)
    1-2 parts perlite
    garden lime
    controlled release fertilizer
    micro-nutrient powder (substitute: small amount of good, composted manure

    Big batch:

    3 cu ft pine bark fines (1 big bag)
    5 gallons peat
    5 gallons perlite
    1 cup lime (you can add more to small portion if needed)
    2 cups CRF
    1/2 cup micro-nutrient powder or 1 gal composted manure

    Small batch:

    3 gallons pine bark
    1/2 gallon peat
    1/2 gallon perlite
    handful lime (careful)
    1/4 cup CRF
    1 tsp micro-nutrient powder or a dash of manure ;o)

  • zeckron
    12 years ago
    last modified: 5 years ago

    Technically bob you're right b/c a cubic foot is about 7.5 gallons (according to google calculator). So yeah, the ratios are a little off.

    However, I'm assuming that when you're dealing with a large volume such as is listed above it would be a little tedious, time consuming, and difficult to get things precise. Al probably mixes up several of his large batches each year. I just spent 2 hours screening my latest pine bark earlier this morning. TEDIOUS! Let me tell ya, it was fun when I did it for the first time last week. Today it was a major drag.

    Dealing with huge quantities can only be fun for so long! :)

  • tapla
    12 years ago
    last modified: 5 years ago

    You're right, Bob. I've addressed this a few times upstream. I usually use somewhere around 5 pine bark fines, 1 peat, 1-2 perlite, plus the other ingredients, but it really wouldn't matter too much if you used the 3:1:1 ratio. It would still drain immensely better & hold much more air for longer than primarily peat soils.

  • wi-northernlight
    12 years ago
    last modified: 5 years ago

    Thanks for clearing that up for me. I thought I had read something about a correction to 5:1:1 but couldn't locate the post to clarify and I've got a batch waiting for me to finish.

    Is my estimating correct that with this recipe you would use about 1/2 cup CRF per cu. ft of mix and about 1/4 cup lime per cu. ft. of mix?

    Also wondering about the screening aspect. I've screened my peat at 3/16" but my bark fines (Greensmix - so glad to have them) looked pretty good right out of the bag. Do you screen the peat AND the bark fines? What size screens do you recommend.

  • tapla
    12 years ago
    last modified: 5 years ago

    Yes - the lime & CRF are about right. You only need to be close on your ingredient volumes. It's not too critical.

    I don't really screen peat for size. Rather, I push it through a 1/4" or 3/8" hardware cloth soil sieve to break up or "strain" the large chunks and sticks from the rest of the peat.

    I have 2 sets of 5 screens that I built & use regularly. 1 set is about 24" square and 3-1/2" deep - the other is about 15" or 16" square and about 2-1/2" deep. They are hardware cloth in 1/2, 3/8, 1/4, 1/8, and insect screening. When I'm using pine bark, I only screen the bark for my soils that I use on woody plant material and that will need to last more than a single grow season. I use screened, uncomposted bark in these long term soils. I discard (in the gardens or beds) all that passes through an 1/8" screen and all that remains above a 1/2 or 3/8 screen, depending on what size plant/pot combination I'm using the soil for. I use unscreened, partially composted pine bark in all my veggie & "pretty flower" plantings or any other short term plantings.

    Lately, I've been fortunate enough to be able to find 1/8 to 1/4 prescreened fir bark at $15/4 cu ft. I've been using this pretty exclusively in my long term soils with very good success and minimal effort (prescreened).

    Al

  • wi-northernlight
    12 years ago
    last modified: 5 years ago

    That clears it all up for me.

    Thanks to Al and zeckron for the help and advice!

    : )

    Bob
    WI-Nlight

  • amyben
    12 years ago
    last modified: 5 years ago

    Shouldn't this paper be required reading for container gardeners? Let's send it to the first page, at least, for fall and winter preparation for spring.

  • magothyrivergirl
    12 years ago
    last modified: 5 years ago

    I used Al's formula for my containers! Wonderful results -even in the drought in the NE. I also amended a spot in my yard where grass would never grow & it was matted w/ thin roots and very, very poor drainage. I didn't have the correct amts of all the products for the 3:1:1 ratio - just sorta eyeballed it using up the leftover pine bark - sorta made a raised bed - and for the 1st time in 7 years that area is growing. Planted a rose bush, 2 elephant ears, moved plants from other areas and it all looks great - considering the heat, drought & I did this in July!
    Al, I love this soiless mix! I gave a copy of it to the guy at the farm supply where I readily found the ingredients - hope you don't mind - I gave credit to you and this site - I kept going back for more pine bark & he was curious - he gave me an uprooted Rosemary plant - it did great in the mix. We live in the "suburbs" but have a great family owned Farm equip & supply feed store - lucky me! I am horrible at fertilizing - so nothing got anything extra - except alot of water. Just wanted to tell you Thank you!!!!

  • tapla
    12 years ago
    last modified: 5 years ago

    Oohhh! Thank you for sharing your success with us, M! Everyone loves kind words, and I'm no exception. I'm glad you're gaining a feel for soils, & I'll hope now that you expand your base to include some knowledge of plant fertilizers and nutritional requirements so you are even more successful. Combine the above with a good watering technique & you'll be unstoppable! ;o)

    Take care.

    Al

  • magothyrivergirl
    12 years ago
    last modified: 5 years ago

    Al, I 'm glad you got my little Thank you note - I do have a question, if you don't mind. Because my containers freeze & break, I try to empty them before winter for storage. I think you said we can get a 3 yr cycle out of this mix. Do you recommend just dumping all the good mix -minus the plants (and any that had bugs or problems) together in a big trashcan and store til spring? Then I was thinking of giving it a boost of some of the nutrients and slow release fert. before the next plantings. What do you recommend?

    I did get some mildew on some of my annuals - it was from the very humid nites & high nite temps - so I wasn't going to combine that mix - but I am going to reuse it.
    Also for the wick, I used a blue micro fiber cloth that I cut into stripes- I have alot of hanging containers - so they were good for conversation - until the theory went way over most peoples heads. Not that I am that smart -I had to read your info about 10 times until I got it. I will never go back to store bought soil. I love it!
    Thanks again for sharing your wonderful recipe and all your time spent answering these questions.

  • tapla
    12 years ago
    last modified: 5 years ago

    You're welcome. Thanks again, for being so kind.

    Some thoughts I offered in another, older threads on this forum. They should pretty much answer your question, and may even be quoted in the text somewhere up this thread (if so, I apologize for the redundancy):

    In my estimation, the only case to be made for reusing container soils is one of economics, and you'll never find me argue against making that decision. If you can't afford, you can't afford it. That said and setting economics aside, you might decide to reuse soil for reasons other than economical. Perhaps the effort involved with acquiring (or making your own) soil is something you might not wish to go through or be bothered with.
    In any case, it would be difficult to show that soils in a more advanced state of structural collapse can somehow be preferred to a soil that can be counted on to maintain its structure for the entire growth cycle. So, if the economic aspect is set aside, at some point you must decide that "my used soil is good enough" and that you're willing to accept whatever the results of that decision are.

    All soils are not created equal. The soils I grow in are usually pine bark based & collapse structurally at a much slower rate that peat based soils, yet I usually choose to turn them into the garden or give them over to a compost pile where they serve a better purpose than as a container soil after a year of service. Some plantings (like woody materials and some perennials) do pretty well the second year in the same bark-based soil, and with careful watering, I'm usually able to get them through a third year w/o root issues.

    Watering habits are an extremely important part of container gardening. Well structured soils that drain well are much more forgiving and certainly favor success on the part of the more inexperienced gardeners. As soils age, water retention increases and growing becomes increasingly difficult. If your (anyone's) excellence in watering skills allows you to grow in an aging medium, or if your decision that "good enough" is good enough for you, then it's (your decision) is good enough for me, too.

    The phrases "it works for me" or "I've done it this way for years w/o problems" is often offered up as good reason to continue the status quo, but there's not much substance there.

    I'm being called away now, but I'll leave with something I offered in reply on a recent thread:
    "... First, plants really aren't particular about what soil is made of. As long as you're willing to stand over your plant & water every 10 minutes, you can grow most plants perfectly well in a bucket of marbles. Mix a little of the proper fertilizers in the water & you're good to go. The plant has all it needs - water, nutrients, air in the root zone, and something to hold it in place. So, if we can grow in marbles, how can a soil fail?

    Our growing skills fail us more often than our soils fail. We often lack the experience or knowledge to recognize the shortcomings of our soils and to adjust for them. The lower our experience/knowledge levels are, the more nearly perfect should be the soils we grow in, but this is a catch 22 situation because hidden in the inexperience is the inability to even recognize differences between good and bad soil(s).

    Container soils fail when their structure fails. When we select soils with components that break down quickly or that are so small they find their way into and clog macro-pores, we begin our growing attempts under a handicap. I see anecdotes about reusing soils, even recommendations to do it all over these forums. I don't argue with the practice, but I (very) rarely do it, even when growing flowery annuals, meant only for a single season.

    Soils don't break down at an even rate. If you assign a soil a life of two years and imagine that the soil goes from perfect to unusable in that time, it's likely it would be fine for the first year, lose about 25% of its suitability in the first half of the second year, and lose the other 75% in the last half of the second year. This is an approximation & is only meant to illustrate the exponential rate at which soils collapse. Soils that are suitable for only a growing season show a similar rate of decline, but at an accelerated rate. When a used soil is mixed with fresh soil after a growing season, the old soil particles are in or about to begin a period of accelerated decay. I choose to turn them into the garden or they find their way to a compost pile.

    Unless the reasons are economical, I find it difficult to imagine why anyone would add garden soils to container soils. It destroys aeration and usually causes soils to retain too much water for too long. Sand (unless approaching the size of BB's), has the same effect. I don't use compost in soils because of the negative effect on aeration/drainage. The small amount of micro-nutrients provided by compost can be more efficiently added, organically or inorganically, via other vehicles.

    To boil this all down, a container soil fails when the inverse relationship between aeration/drainage goes awry. When aeration is reduced, soggy soil is the result, and trouble is in the making.

    I've mentioned before that I don't post here to get people to convert to a particular mix or blend of soil. I post what I know will work very well for anyone who can get appropriate ingredients & modify the mix to suit their climate & other cultural conditions. If you use a mix that guarantees good aeration for the expected life of the planting - you're in good shape. Most peat based mixes will not work well in extended life plantings. Conifer bark based mixes, on the other hand, retain structure for much longer periods.

    If you still have questions, please don't hesitate ....

    Al

  • amyben
    12 years ago
    last modified: 5 years ago

    I was so happy to find this article when I was a newcomer, that I must send it to the first page. I guess soon it will max out and someone will re-post. Until then, let's keep it handy.

  • tapla
    12 years ago
    last modified: 5 years ago

    Thanks, Amy!

    This thread is ready to be terminated, so I will provide a link to a new thread for any interested. Scroll down to the next posting for the new link.

    Al

  • tapla
    12 years ago
    last modified: 5 years ago

    Click on the link below to view a continuation of this thread in part IV.

    Al