Hello!

Bark is used primarily as a filler, but it is excellent because of its durability,
chemical composition, and moisture retention (averaging somewhere between turface and granite).

For a gritty mix, the bark should be uncomposted. You want a long-lasting mix, after all.

Nitrogen immobilization applies more to hardwoods and sapwood than bark (which contains suberin).
I've never experienced an issue.

Josh

N immobilization is less a concern in the gritty mix than in most container media because the volume is 2/3 inorganic, and for the reason Josh mentioned - the bark is rich in lignin and suberin - a lipid that resists microbial activity and helps ensure a gradual breakdown of the hydrocarbon chains that make up the bark particles.

As Josh mentioned - the bark is a filler, and it helps make the gritty mix easier to swallow. ;-) What I mean by that is, when I first started to describe the ease with which you can grow in the gritty mix, I don't think ANYONE would have believed you could grow perfectly healthy plants in an inert mix of Turface & grit - even though you can. The real reason I include it is because it's so much cheaper than Turface or crushed granite. It has roughly the AVERAGE water retention of Turface & grit combined, and won't break down, causing water retention problems before the plant is so rootbound it should have already been repotted.

Finally, it's very easy to compensate for any N immobilization in fast draining soils because you fertilize so often. In slow draining soils, it's difficult. The reason is, as you water in sips & the N is depleted, the other salts are building in the soil. Your choices are: A) Fertilize to fix the N deficit and suffer the effects of high TDS/EC due to the OTHER nutrients supplied at the same time (IOW, risk fertilizer burn). B) Live with the N deficiency & its effects. C) Water properly (flush the soil when you water) and fertilize regularly, but risk the higher probability of root issues and compromised root function.

See why we like well-aerated and durable soils? None of these issues apply.

Al

I am curious Al, when is it ideal to use the gritty mix instead of the other soil mixture you also have? (and/or vice versa)

Gritty Mix is ideal for woody plants and long-term plantings (going 2 - 3 years between re-pottings).

The 5-1-1 is ideal for annuals (container floral plantings), vegetable crops, and vigorous
plants that will be re-potted after a season's growth - sizing up conifers or maples, for example.

Josh

Sorry to barge in, but this news about the bark in gritty mix is new to me. Can I really just make gritty mix using just turface and granite? Wouldn't that make the mix basically last forever? That sounds easier than having to worry about the bark breaking down over the years when repotting.

Jared

You can do that, and it will work just fine. The only caution is you need to be extra vigilant you are supplying all the essential elements needed for normal growth, since there will be no organic fraction to break down and supply any of the elements needed in trace amounts.

Al

Alright thanks for the heads up Al. Looks like I'll have to find some bark for my mix then. I don't know enough about fertilizer to provide proper nutrition.

What I said shouldn't be read to say that if you use bark, proper nutrition is no longer a critical issue; it will always be critical for container culture. The organic component, bark, offers only a small cushion, so you'll still need to shoulder the responsibility for making sure all the essential nutrients are being furnished to your containerized plants.

Al

Here is a link that might be useful: More info on fertilizing containerized plants if you click me!

I'll be sure to read that article a few more times so I can absorb all of that great information. Thanks for all the help!

Jared

I like the idea of having a medium that will last basically forever, however, if the bark has "roughly the AVERAGE water retention of Turface & grit combined", it seems plausible to use a mix of 100% uncomposted bark in such a mix. Then when repotting down the road, recycle the now partially composted bark into a 5-1-1 mix. Of course, this would require frequent enough repotting as to not overdo your bark's lifespan, thereby comprimising aeration and soil structure. But that's the idea with repotting, we want to "insure they can grow at as close to their genetic potential within the limits of other cultural factors as possible". I think that, if feasable, this would be a very easy, cost effective alternative to the traditional gritty ingredients, as well as providing a reusable component to the 5-1-1. Am I overlooking anything?

You haven't committed a sacrilege at all ;-)

I use uncomposted bark in the 5-1-1 and it does increase the longevity of the mix.
I have no doubt that if you really wanted to go through the trouble of screening out
the bark, you'd be able to re-use a fair amount. At the least, you could mix in some
old with the new, and stretch your mix out that way.

Josh

My appologies if I've misunderstood your reply Josh, but I'm not sure we are on the same page. My question was regarding using an "all bark gritty" comprised of 100% screened uncomposted bark. My intention would be to use it down the road, at repotting time, in it's entirity, as a recycled component (assuming it would now be partially composted) of a 5-1-1 mix . Then use a new batch of the "all bark gritty" to repot with.

Water retention may be slightly different, but I'm thinking, not all that much. Here's my logic:

If the retention of bark(A) is equal to the average of Turface(B) & Grit(C) then:

A = (B+C)/2

If this is true then:

3A = A + B + C

This would imply that 3 parts of bark would have the same water retention as 1 part bark + 1 part Turface + 1 Part Grit. We've already established that bark is durable, provides structure, and allows for proper aeration. Have I overlooked some detail that would cause a fundamental problem with this cost/space/resource saving approach?

"A = (B+C)/2

If this is true then:

3A = A + B + C"

You can't argue with that logic, lol. I see your point though, and it makes sense. There are just a couple downsides that I see. First, you lose the ability to adjust water retention in the mix. (Although you could add a bit of Turface or granite if it were a problem.) Second, when the mix does begin to break down, it will happen pretty quickly since there is no inorganic portion to diffuse the effect. If you're willing to deal with those issues, I don't see why it wouldn't work.

I think I remember Josh growing some plants in all or mostly bark, so he may have something to say about it as well.

"You can't argue with that logic, lol."

No offense but lol or not, the logic is sound...lol. In a group of 3 values (A=15, B=10, C=20), of which 1 is the average of the other 2 (A = (B+C)/2), 3 times the average (3A = 3*15 = 45) is equal to the sum of the 3 values (A+B+C = 10+15+20 = 45). Now, whether it's practical or not in this application is another story.

I thought about the inability to adjust the retention. I think that it could be accounted for by simply adjusting your watering schedule to suit the plant, without adding material that would need to be removed prior to reuse.

Interesting point about the inorganics diffusing the effect of decomposition, I hadn't really considered that. If uncomposted bark was used to begin with though, I would think that you could get a year out of it before it was ready for the 5-1-1. Although, I do not have the practical experience to confirm this. Does anyone have thoughts on that?

Keep in mind that, at least initially, I think that I would try this with my tropical type houseplants, therefore, direct sun, temp, humidity etc would not be a concern.

Rereading that bit, I can see how it might come across as sarcastic, but I didn't mean it that way. Your logic is sound. I was just laughing at the use of a mathematical proof. I'm sorry if I caused offense.

I'd imagine you could get at least a year out of an all bark mix, if not two, but I've never tried it. We'll see what others have to say.

I just try to do my best by others through helping them understand certain principles that I think have the potential to improve their growing experience. There are a number of ways to arrive at the same end.

Removing the inorganic fraction of the gritty mix will leave you with something very much like the 5:1:1 mix. We all know that works well, so there is little reason to think some variation on that theme couldn't be pressed into service with favorable outcome for short term plantings.

.... best way to tell is to remove the theory by putting it to the test of practical experience.

Al

Hey, guys.

DaMonkey, it was I who misunderstood your post. I see what you're asking now.

Penfold is correct that I grow a couple plant types in all bark or mostly bark mixes.
These plants are Hoyas and jungle cacti - Christmas Cactus specifically. As you can see,
these plants are suited to an arboreal existence, and thus the all-bark medium makes sense.
I wouldn't hesitate to use an all-bark mix for (certain) Orchids, either. However, these
plants are typically potted in smaller volumes, or in containers that facilitate drying,
so the impact of the bark's moisture holding qualities isn't as great.

Out of the bag, uncomposted bark still has a lot of fine bark dust.
By removing the bark dust (screening and rinsing), you get a product that lasts a long time.
I have a fern in a mix of bark, perlite, and pumice that will be 3 year's old in May.
The bark is still quite discernible as bark.

I have also planted in a simple mix of bark and perlite. I used this to collect
Maple seedlings, essentially slipping the dug up root-ball into the bark/perlite for a season.

That said, I would not personally use an all-bark mix because of the way the lower layers
will compact and hold moisture. I think you need something to displace the excess water volume
and maintain structure (like Perlite or a non-porous grit).

You might also discover that the upper layers of bark dry out to the point of hydrophobia
before the lowest layers are ready to be watered again.

Josh

Hi guys,
Thanks for all the responses.

Penfold,
It's funny, after I posted that I thought, "I wonder if he was just poking fun at my use of math to explain this..", haha, no offense taken, I hope I didn't offend as well. Thanks for the input!

Al,
You're absolutley right. I'm just thinking out loud a bit I guess. Now that I have some knowledge and opinions, I'll use them practically.

Josh,
Great point about the "arboreal existence" making sense with the all bark recipe. The rest of your post is strong indication that there will be inherant issues over time with most plantings minus the addition of inorganic materials. This also concurs with Penfolds statement regarding inorganics diffusing the effects of decomposition. That being the case, it would be contradictory to my initial purpose of reducing waste and the overuse of resources (time and money included) by easily recycling the all bark mix into a 5-1-1 application.

I'll think about it practically and move forward, if I so desire, without broaching the topic on the forums again unless I have any successes or failures to report.

I will also continue to keep my head up for the traditional ingredients for the gritty in managable sizes at managable prices.

Who am I to tinker with perfection anyways!!!

LOL

Good stuff guys, my mind is racing!!!

I'm not sure if it's the thread or the cuban coffee, but it's racing!!!

HAH!

Thanks!

so how about screening the Turface and Grit with 1/8 screen and growing in that alone? would that be better than screening through insect screen since particle size would be bigger? also my pine fines(bag of soil conditioner)are slightly larger than fingernail size, will this make a big difference... if we're basically using it for "filler" could it be a little larger than ideal and still be Ok? I think I've read that the smallest particle of the mix will determine water retention so I was thinking the bark size might not mean so much as long as the Turface and Grit size were correct (around 1/10 to 1/8). I screen the Turface and Grit with screen about 1/10 hoping to keep particles as large as possible.

There's no reason that you couldn't do that, however, bigger isn't always universally better...in this case anyways ;~) A fraction of your particles down to 1/16" or so are beneficial in many cases. A mix of this particle size and composition ~may~ have less water retention that you expect. Depending on what you are planting in this mix and the environmental conditions the planting will be subject to, you may find that the watering requirements may higher than what is convienient for you. It all goes back to what's best for the planting vs. what's best for the grower, as it has been said so many times here. You may want to make a very small batch, try it out on a planting or two for a few weeks, and go from there. I expect that you will find, as I have, that you will not find the exact recipe that you are looking on these forums. You will find it in your back yard through your own experimentation. Have fun with it!!

PJ

Last fall I started growing some plants in a mix of Turface/Floor Dry (similar materials I use for their different colors), and granite grit. It's too early to make a verdict yet, but one thing that concerns me is the particle size seems a little too small to me, particularly the Turface/Floor Dry. Some bark would help increase the average particle size. You could screen the Turface with a larger mesh, but you may lose well over half the product.

As for the bark, some people say it may migrate to the top of the container if it is significantly larger than the rest of the ingredients. I've never seen this happen in my mixes, but it may be something to consider.

I've been a "student of Al" for quite some time, and I find the most important pieces to the whole puzzle are understanding the concepts fully... knowing why we're using the ingredients we use, and knowing how they work within the confined space of containers.

If we understand the basic science of plant/root growth, the basic physics of how water moves through mediums, and what each ingredient brings to the mix, in terms of moisture retention, etc... we can play around a bit with our ingredients, ratios and mixes to get the perfect medium for each individual plant or situation.

I, myself, tweak my mixes depending on type and size of plant and pot, the environment it will be placed in, etc...

Uniformity of particle size is definitely beneficial. As we know, it's near impossible to get every particle we're using in a medium to be the exact same size. But keep in mind that when one ingredient is really large, the other ingredients that are much smaller just fill in the spaces around that one really big ingredient, defeating the whole purpose of the concept.

Additionally, skipping the steps of rinsing away dust, or sifting out the too large and too small particles will also serve to defeat what you're trying to do.

The idea... at least when we're talking about the Gritty Mix... is to keep our particle size fairly comparable.

I think we each have to take into consideration where we live, too... and what our climate is like, whether we're growing indoors or out, the amount of light we have to offer, general humidity, and all those other pesky little variables that will differ for each of us.

As example, I live in the Midwest, grow using the Gritty Mix mainly indoors, in a 2nd floor studio type apartment with vaulted ceilings. My main light source is an eastern window alcove/dormer. Because my husband works with a lot of electronics and computer technology, the humidity has to remain drier than most plants like. Running a humidifier is out of the question. Also, because of the AC/heat unit types I have to deal with, maintaining a constant temperature is kind of difficult.

So, we will each have our own demons to conquer, so to speak. And we have to give all these variables a little thought when planning our mediums.

It may take a little bit of experimenting and time before we figure out exactly what formula works best for each of us, all things considered... but don't get discouraged... as long as you have the knowledge to draw from, the skill to grow beautiful, healthy plants will follow.

Since I only need to mix small batches of Gritty Mix at a time, I use the small or medium sized bags of 100% fir bark available at PetsMart, packaged as ReptiBark reptile bedding. I use coarse perlite I obtained in a large bale at our local garden center. And I use Manna Pro Gran-i-Grit poultry grit from Rural King, which is a large farm oriented store found in the Midwest. It's 100% crushed granite pieces.

Sometimes, I use turface... and sometimes, if I need a little more moisture retention, I add a handful or two of quality potting soil from a bag... usually a commercial type, like Sunshine.

I've found MiracleGro potting soil to be very different bag to bag, no uniformity, too peaty, and in my opinion... just junk. I find it a complete waste of money, and I often find it to be moldy and include things I'd rather not risk my plants to.

In any case, I think it's important to understand that it's the CONCEPT of what Al is teaching that is most valuable. If we understand how and why we're doing what we're doing, and we take into consideration the individual variables we have to deal with, we'll be fine! We have all this great knowledge at our fingertips, a ton of help in the form of all these great people here, many with lots of experience... there's no reason we can't all have thumb of green!

And incidentally, a green thumb is nothing more than applied knowledge. It's got nothing to do with luck or magic. It's all knowledge.

so if a Turface-Granite only mix is used and FP is used, would i still continue watering and fertilizing just as if the bark were still in the mix or would it need to be stepped up?? Also i will be mainly growing Maples (2 Shishigashira, 2 Crimson queens, 3 Waterfall, and 2 plain maples) im probably going to use the bark anyway since i already have it and i think i'll try potting 2 of the trees in the Turface-Granite only mix just to see how it turns out

Given the difficulty that many have finding the unaged pine bark fines for the gritty mix, why not use just Turface-granite? Would it be that hard to meet the nutritional needs of plants in this completely inorganic medium?

There is no reason you can't use granite & Turface & end up with perfectly healthy plants. Since Turface is a little smaller than is ideal, and it retains more water than bark, you might want to skew the ratio a little to favor the grit fraction - like maybe 3:2 or 2:1, grit:screened Turface.

I wouldn't give up on the bark so easily, either. I can't count the number of times I've found bark in another state and within a short drive for growers who said they couldn't find anything suitable for one of the mixes .....

Al

Maybe it's just a California product, but I buy Earthgro Decorative Groundcover Bark in the "fine" size at Lowe's and Home Depot. It's redwood bark, but I've bought fir bark sold as orchid bark at my local garden center too. The orchid bark costs twice as much, but it's still pretty cheap. I also picked up (er, not without difficulty) two 50lb bags of gravel at Lowe's this morning for $2.73 each.

I checked with Scotts: Unfortunately the Earthgro Decorative Groundcover Bark is only available on the West coast. I can't seem to find an inexpensive alternative for un-composted/un-aged pine bark fines here in the Raleigh/Chapel Hill/Durham part of NC. Still searching...

If you haven't already, try:

AMERICAN SOIL & MULCH
NC HIGHWAY 55
CARY , NC 27511
(919) 460-1349
http://www.americansoilandmulch.com/

The website indicates that they stock pine bark fines and various cuts of pine bark mulches!

Hope that helps!

PJ

Hi, I'm from Australia. Having read about both the gritty mix and potting mix on this forum I would like to try both but can't easily source Turface or crushed granite. We have attapulgite clay and crusher dust which is crushed basalt rock or blue metal. I have noticed our native tree seeds freely germinate in the crusher dust and any succulent leaves which fall under my benches seem to set roots fairly well. Could I substitute attapulgite clay for Turface and crusher dust for the crushed granite?

There is one supplier of Turface in Australia - Sage Horticultural in Melbourne (they have a website).

An alternative that I have used successfully is Mt Sylvia diatomite (kleensorb) 2-7mm.If you want to use it let me know where you live and I can try and locate it,

Alan, Adelaide

Thanks Alan.oz, we're in SEQld. I'll try Sage Hort and see if I can locate Mr Sylvia diatmomite in our area.
You're a bit drier in SA than we are here, we get fairly high humidity and wet summers, do you think this mix is suitable for outdoor container plants up here? I grow mostly foliage plants like marantas, aroids and gingers. Leaching is also a big problem with all the summer rain, keeping up the nutrients is constant work. And have you tried the other mix, 5:1:1?

Gingers and some aroids can get big so I would suggest growing them in the 5:1:1. It has also worked fine for me.

I mainly use gritty for smaller slow growing plants like cycad seedlings and Amaryllid bulbs that are sensitive to overwatering.

Thanks for that, I have contacted Mt Sylvia and they have a distributor in Ipswich I will get it from.
Can I use perlite as a substitute for crushed granite? Or would crusher dust be better?

> Posted by penfold2 on Feb 16, 12
> mix of Turface/Floor Dry... and granite grit.
> It's too early to make a verdict

Penfold, verdict please.

Hey Al, just wanted to make sure that 2 years later all this advice is current.
Some of my gritty mix is now just about 2 years old also. It seems to be holding up but I got to thinking, like some of those in this thread, that it sure would be nice to have a permanent mixture for the long term plantings, by withholding the organic ingredient. Plus it's one less ingredient to have to buy and later screen. I see your main purpose for including it was to lessen the fears of potential gritty mix users that plants couldn't possibly grow in it. It's also used to average the particle size and water retention of the two other ingredients. I use FP to fertilize and look after my plants often enough that this isn't a fear of mine.
I utilized a 1:1 ratio of Cherrystone:Turface for two basjoo banana trees planted in the ground here in zone 4. I have heavy clay and when I grew them the last time, they grew slow and their corms later rotted over the winter. I also don't think I properly watered/fertilized.
So this year after reading your posts in the link below, I upped the FP by 4x to 1 tsp of FP per gal, rather than 1/4 tsp I used before, and brought the PH down to 5.5 with vinegar rather than the unacidified 7 of my tap water. I know you water with this dosage weekly with outdoor plants but I watered with it almost every day during the hot summer days with no apparent issues. I found that this amount of FP was too much for the indoor plants though...
I also experimented with digging about a 4-5 gal hole where I planted the bananas and poured in the 1:1, so at least some of the soil near the corm and roots didn't have to deal with the heavy clay. The plants grew waaay faster this summer and hopefully it'll help the stems/corms survive this winter.
I utilized the 1:1 before reading your post in this thread about using a higher ratio of granite/cherrystone to compensate for the small particle size of the turface. Even though the basjoo's did great in the 1:1, I'm guessing in a pot, a proper ratio (2:1 or 3:2 like you mentioned) would be a bit more important. Is this a safe assumption?

Here is a link that might be useful: Fertilizing advice

Hello,

I'm probably not posting this message in the right place, it's a message for Al Tapla.

I have read many of your incredibly creative, wise posts spanning over many years and admire you enormously, not just your intelligence but your generosity with your sharing your knowledge of growing plants and nurturing growers too. I have struggled with feeling nervous to reach out and ask you or your garden forum community for help with the Gritty mix because you certainly don't need another newcomer needing you to repeat yourself for the bazillionth time.

I tracked down the Turface (MVP), the Granite, and stumbled on the pine bark fines and the sifting. The bark fines I used were from a big cheap bag of soil conditioner, and all the sifting I did was with a big kitchen pasta sieve. I rinsed off everything as I sifted. When I finally repotted all my plants into my attempt at the Gritty mix, everything (geraniums in particular) acted like I was overwatering, curling growing yellow leaves, which I know in the gritty mix is crazy. My rubber plant didn't do much at all. All my plants were root bound, or needing to be brought indoors. I couldn't tell when I needed to water, so maybe I watered too much. Maybe every two or three days instead of four like I think Al might do.

I kind of gave up and repotted everything in a mix of Miracle grow products and I hate it, very slow draining and I feel idiotic and defeated every time I look at the bags of MVP in my garage.

Any chance that a successful Tapla follower could (or Tapla himself) could help me to fix my gritty mix? Maybe I should just buy the gritty mix online and see and feel how its different from what I created?

Anna

Hi, Anna, how soon did the yellowing occur? How healthy were the plants when you re-potted them? And at what time of the year did you re-pot?

Did you resume fertilization after the re-potting?

Josh

So after spending $100's on reptibark and sifting and crushing and sifting 70 gallons worth please tell me that bark helps the mix in some way. (Al said you can grow just fine in just Turface and granite.

Also how long does bark last and how long does Turface last?