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100% Synthetic Potting Mix?

Posted by Jay-Part-Shade 10A Los Angeles (My Page) on
Tue, Jun 3, 14 at 19:45

Hey guys, I have about 50 plants in the 5-1-1 mix and I'm liking it.

That said, I'm thinking about a 100% synthetic mix. I'd like to replace the bark and peat with something that doesn't break down. I use air-pruning pots and grow mostly fruit trees and some vegetables in sizes up to 15 gallons. Because I don't need to root prune, I'd like to leave the trees i the mix indefinitely and not have to worry about the bark breaking down.

I've been looking at Grodan (rockwool) mini cubes, Growstones, turface and other substances. Since 5-1-1 and gritty act as a quasi hydroponic medium, I figure there should be something out there that has the right water retaining characteristics. Most of the hydroponic mixes are made for recirculating or constant drip, not leaving trees outside and watering once every few days.

Anyone tried this?


Follow-Up Postings:

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RE: 100% Synthetic Potting Mix?

I have been growing all of my trees, succulents, bonsai, and house plants in all synthetic for a few years now, with good success. Currently I use only turface and quartz grit, in varying ratios. I will be adding lava rock to my mix shortly. Careful attention is needed with fertilizing though, as there is zero nutritional value in all synthetic mixes.

As for your theory on air pruning roots; I am quite skeptical about that. If you can try and visualize how roots grow, you'll note that they grow outward, growing thicker and thicker near the trunk, with the feeder roots growing on the ends of the roots, farther and farther away. You'll end up air pruning the feeder roots off so many times that your pots will be filled with thick, unproductive roots.

Joe


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RE: 100% Synthetic Potting Mix?

Hey Joe,

Good info, thanks! Ideally, I'd like to avoid the grit since it's super heavy -- 15 gallon pots are already a pain to move. Any light weight alternatives?

And would you say your turface/grit mix is closer to 5-1-1 or Gritty? Ideally, I'd like to get closer to the 5-1-1 water retention since that's what seems to work for my area and plants.

Regarding root pruning, there's quite a bit of research and discussion about the root pruning bags (Root Pouches, Smart Pots, Geopots, etc.). I've used them a few years and they work great, though you make a good point about the upper limit of root size. I imagine they work similar to how hand pruning works -- the big roots grow out of the bag, die, causing new roots to develop. But there's probably a point where roots have taken over the entire bag requiring a major hand pruning.


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RE: 100% Synthetic Potting Mix?

If you use diatomaceous earth you will give yourself a lot more options. Check this promo info out. I know it is to sell the product, but I doubt the info is false. DE holds more water then turface, will last longer too, like about 50 thousand years. I myself use Optisorb, the size is just about right. A lot of powder though, but you can use that as a pesticide.
A light substitute for grit would be cork, but horticultural cork is very pricy.

Here is a link that might be useful: DE info


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Tue, Jun 3, 14 at 23:00

First off instead of saying synthetic let's go with inorganic. It's more inclusive. Pumice or scoria would probably be the best base and they certainly aren't synthetic (although the bag of pumice I have says organic lol orly?). Then add calcined clay or DE to raise the water retention. I don't like the fine DE as it seems to not have enough air space and settles in the bottom too much. If you find a source of coarse axis in LA let us know. I would love to try some out. Turface MVP is available at Ewing and the latest batch didn't even need sifting. I would start with 3 scoria:1 turface. You can get 3/8 scoria (cinder) at sunburst in Irwindale for about $100/yd.

Your hypothesis about never having to do root work is wrong. Yes, those pots will prevent girdling but you will still have to occasionally rejuvenate the root ball. They aren't magic.


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RE: 100% Synthetic Potting Mix?

The moisture retention of the turface and grit combo I use is adjustable by the ratio used. 50:50 is what I've used for succulents, but I am finding that it holds too much moisture, so I'll be reducing the turface. The turface grit mix is a gritty mix in every sense of the word, but don't be fooled.....it can hold a lot of moisture.

As for the weight, well, I suppose you could use perlite instead of grit, but it floats, and blows away easily, which isn't a big issue if it's buried in the mix and top dressed. DE would work too, but it must be the fired kind that won't break down though. Also, as I said, I find that turface holds a lot of moisture, in fact, too much if you don't add grit, or not enough, so using DE for added moisture may be overkill. Mind you, those mesh type pots will dry out faster too.

As for the roots, well, I don't have experience with the bags and such, only regular old containers, so I can't advise based on personal experience. However, having grown trees in pots for about 15 years now, I've done plenty of root work, and it's not from the outside in. I usually cut out the largest roots at the base, which takes a section of feeder roots with it each time. I can't see it working without soil removal and interior rootball work. I can see where the roots would indeed die off as they leave the container, and regenerate new ones, but those main transport roots will still continue to grow, eventually crowding everything out. Keeping trees alive in containers for more than a few years requires root work, and I don't think there's any way around that.

With that said, this hobby is great for not-so-scientific science, experimenting, and trying new things, so if you have a plan, give it a shot. What's the worst that can happen? You might kill a plant or two, or twenty, but you'll still be alive to try plan B, then plan C, and so on. But, you MUST report back, cuz we gotta know the results!

Joe


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Tue, Jun 3, 14 at 23:16

The recirculating hydroponics systems use a very coarse particle size in order to water frequently and still maintain enouh air. When you decrease the particle sze you not only don't need to water that frequently (multiple times per day) but it would be detrimental.

If you want to find info about something close to what you are planning, search "missouri gravel bed."


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RE: 100% Synthetic Potting Mix?

Hey Nil,

Great info! Exactly what I'm looking for, and good points about inorganic.

Other than cost and convenience, is there a reason more people don't replace the bark/peat with pumice/lava/turface? The big issue with the 5-1-1 I've found is there's a bell curve of when the mix is best suited for the plants after it's brewed for a few months and before it decomposes into mush. I think I've seen some of your plants before - what do you use?

Below is a chart from Growstones about water/air retention. I'd be great to include pumice/lava/turface/etc. so we know where they stand. I'm having a hard time finding this info. If anyone has it, I'll make another chart.

And funny enough, if you're in Mt. Washington, I'm probably 5 mins from you in Atwater.


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RE: 100% Synthetic Potting Mix?

Optisorb has course DE, you have to remove the powder, but most of it is just about perfect size. I get mine at O'Reilly auto parts. I just scooped this out of the bag.
I use it instead of perlite in my mixes. I wanted more water retention, but with air still in the soil, so far it seems to be working really well!
The various studies on DE show excellent root growth. With turface root growth seems compromised in one study I saw. I can say that the same plants in raised beds with excellent soil, are not doing as well as the same cultivars in pots with DE. Using DE seems to have made a difference in growth rate.
I want my plants to excel, and have been pleased with using DE. I would highly recommend it.

"If anyone has it, I'll make another chart."?

The link in my other post compares water absorption, but not air

This post was edited by Drew51 on Tue, Jun 3, 14 at 23:49


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Wed, Jun 4, 14 at 0:46

Here is some info on media

Here is a link that might be useful: Growing media


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RE: 100% Synthetic Potting Mix?

Hey Joe, very interesting, that was a good read and the price is right $15 for 25lbs! How much do you use in your mixes?

And thanks for the link Nil, that's really helpful. Do you have a local source for the pumice?


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Wed, Jun 4, 14 at 0:55

Joe, the research coming out of Missouri suggests that 40% Turface is an upper limit in 3/8" pea gravel. Mind you they don't sift anything. With smaller grit, I would keep it below 33%.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Wed, Jun 4, 14 at 1:10

There's a thread on pumice here. I haven't priced any of these places out for bulk though.

Here is a link that might be useful: Gardenweb socal pumice thread


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RE: 100% Synthetic Potting Mix?

I've never used granit in my gritty mix, I've always used pumice instead, I've been very happy with it. This year I changed out the Turface for Growstone, I don't have to sift any out, just wash.

I used two sizes of Grownstone in my plumeria mix, so it ends up a 50/50 mix, two sizes of bark and two sizes of Growstone, I did this so the bark would last longer.

So basically I'm saying I think you'd be happy using pumice or Growstone.

Jerry


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RE: 100% Synthetic Potting Mix?

The key is particle size, so using turface without sifting the smaller particles out will cause problems. This logic applies to any other media as well. You'll end up with perched water with small particles. In fact, even turface sifted with bug screen has too many small particles in my experience, and is causing perched water in my 50:50 turface grit mix, which I am in the process of altering. I can say though, that with good watering practices, I've seen some excellent root growth on all of my different plants and trees, so I am not going to agree that turface is no good. As I stated above, this hobby is a never ending experiment, and just when you think you got a top notch mix, something seemingly better comes along.

Joe


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RE: 100% Synthetic Potting Mix?

Nil: great thread on pumice, thanks!

Jerry: that's a nice-looking mix, looking up prices, pumice is vastly cheaper than Growstones. Any reason to go with growstones over pumice or turface? And aren't pumice and turface similar in retaining water? Or is pumice much less water retentive?

Joe: Tiny particulate seems to be a big question. I don't think I can run a gritty mix in my conditions, but 5-1-1 works well. If I'm trying to replicate it without bark/peat, I'd imagine I'd leave dust in?


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RE: 100% Synthetic Potting Mix?

Gritty mixes of any type need to stay gritty.....so no dust. Letting dust and/or small particles in will just fill in the gaps between the larger particles, taking away all of the benefits of a gritty type mix. I understand that the concept of growing in what looks like pea gravel seems out there, and you can't imagine that it would work, but it does. I was once a skeptic, but took the plunge and tried Al's gritty mix, and I got good results. I however don't like using the bark, because it gave me too much trouble with its hydrophobic properties, and my source for it ran dry. But, I am sold on the concept of the gritty mix, and will tinker with it until I find the perfect mix that suites me and my plants. If anything, do a small scale switch, and give it a try on a few trees or plants, and see how it works for you.

Joe


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RE: 100% Synthetic Potting Mix?

Jay, I'm 90% happy with Turface, that and pumice has worked great in my mix. I'm a gritty person and I didn't like sifting out so much of the Turface to get the consistency I wanted, I was always looking for a product just a hair bigger, that's where Growstone came in. So my new mix is bark, Growstone and pumice, this will work for me and my situation.

Joe, I agree with you, particle size is the thing and I wouldn't use the dust or the small particles of Turface, even if I was doing a 5-1-1


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RE: 100% Synthetic Potting Mix?

Joe: Good points, though I can't grow in gritty. I use 5-1-1 because gritty is too heavy and doesn't hold enough water for my trees in fabric bags. My 15 gal pots in 5-1-1 often need water once a day. Ideally, I'd find some inorganic mix that is close to 5-1-1. I'll use gritty for my succulents and cacti.

Jerry: that makes sense about grow stones. I'm trying to get rid of the bark component in 5-1-1 (and peat) -- in 5-1-1, bark is less than 1/2" all the way down to dust. And then there's the peat which is practically dust to begin with. That said, I have no real love for dust, it's a pain. Would adding more water-retentive material like Turface or DE balance out the need for the bark/peat dust? Or am I missing something?


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Wed, Jun 4, 14 at 11:33

I think people get too worked up about the fines. They just use straight pea gravel and turface at U. Of Missouri and have excellent results. I have used that mix in LA with excellent results and there is still some sand in the pea gravel and some fines in the turface (there really aren't that many fines in MVP) I have used unsifted pumice and turface for a green roof medium demo and it worked well. My opinion could very well be different if I lived someplace that actually had rain and humidity though.

According to the Pacific Bulb Society page, growstone has an alkalinity problem that would concern me especially in SoCal since acidity is in short supply.

This post was edited by nil13 on Wed, Jun 4, 14 at 11:42


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RE: 100% Synthetic Potting Mix?

Hey Nil, makes sense it'd work better in LA's dry climate. Do you think an unscreened mix of 3 parts pumice, 1 part turface, 1 part DE Axis would get close to 5-1-1?


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RE: 100% Synthetic Potting Mix?

Nil13, alkalinity was a problem, but they corrected that a couple years ago with a ph buffer in the manufacturing process.

Every grow media has pros and cons, it comes down to each individuals needs and situation. I say have fun with it, be a MAD scientist!

Jerry


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Wed, Jun 4, 14 at 14:48

Since I've never used axis, I can't say.


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RE: 100% Synthetic Potting Mix?

Interesting thread, with lots of good links. Thanks guys.


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RE: 100% Synthetic Potting Mix?

Yes indeed, you CAN grow plants in completely inorganic "soils". I think even Al mentioned once that you can grow healthy plants in broken glass if you wish, as long as you keep up with watering and fertilizing.

Most interesting thread. Lots to consider and think about. It's also good to know that both the gritty mix and the 5-1-1 mix are flexible enough to allow the many ingredient substitutions being mentioned here. Depending on where you live and the types of plants you are growing, there appear to be a large variety of options for building growing media.

TYG


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RE: 100% Synthetic Potting Mix?

The constellation of potting mixes is very large. At the other extreme from synthetic mixes, we have whole families of organic and permaculture styles.

As I've said, I think the fact that all these styles are used by commercial growers means that they can and do work, and provide useful ROI.

There are commercial growers of greenhouse crops using synthetic mixes, and people using compost as well.

Whatever your interest, you can probably find a model that works.


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RE: 100% Synthetic Potting Mix?

In my experience, growing within the confines of a container is very different than growing in a garden setting, in the ground... knowledge I wish I'd had many decades ago when my love for growing plants surfaced and consumed me, so to speak! :-)

Because of the balance Mother Nature is able to provide and sustain, organic growing works very well for a garden setting... but trying to maintain that very same balance within a pot can be difficult.

Mother Nature gives us an entire army of bacterias, fungi, nematodes, worms, insects and other critters, both large and microscopic, all working in veritable harmony to break down organic plant matter into usable food for the plants growing, providing aeration and drainage, etc... those same conditions and balances are not part of container growing, and are difficult at best to provide and maintain for the average gardener.

I've learned to approach container gardening from a more inorganic angle, saving organic growing methods for the vegetable and flower gardens, leading to a better overall success rate for the plants I'm trying to grow.

As far as mediums are concerned, I've learned to mix my own container mediums using Al's recipes and information as my basic guide, adjusting batches according to different variables... such as plant type and size, location of the container, etc...

As Al notes in "Container Soils - Water Movement and Retention XIX"... "Container soils are all about structure, and particle size plays the primary role in determining whether a soil is suited or unsuited to the application.

Soil fills only a few needs in container culture. Among them are: Anchorage - a place for roots to extend, securing the plant and preventing it from toppling. Nutrient Retention - it must retain a nutrient supply in available form sufficient to sustain plant systems. Gas Exchange - it must be amply porous to allow air to move through the root system and gasses that are the by-product of decomposition to escape. Water - it must retain water enough in liquid and/or vapor form to sustain plants between waterings. Air - it must contain a volume of air sufficient to ensure that root function/metabolism/growth is not impaired.

This is extremely important and the primary reason that heavy, water-retentive soils are so limiting in their affect. Most plants can be grown without soil as long as we can provide air, nutrients, and water, (witness hydroponics)."

So, as long as we're providing those things with the medium of our choice, successful growing is within easy reach!

Here is a link that might be useful: Container Soils - Water Movement and Retention XIX


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RE: 100% Synthetic Potting Mix?

I get what you are saying, jodik, but I think in the wider culture compost based mixes are still well represented. I think most "organic" or "organic certified" mixes work that way.

And you know, with my container tomatoes setting fruit above my head right now, I think that it's working for me.

Of course, the other approach may work for you, and that's great.

(Probably a lot of methods can "max out" a tomato in a given space and pot size.)

This post was edited by johns.coastal.patio on Thu, Jun 5, 14 at 10:03


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RE: 100% Synthetic Potting Mix?

Hey Jodi, you mention compaction and retaining good air/water exchange because of structure -- that's why I think a completely inorganic mix would be better. Even though I've been pretty religious with my 5-1-1 mixes, I can tell there's large variables in the quality and (de)composition of the bark and peat. Because of the bark, some trees have excellent root growth, others seem to stall completely.

I'm trying to figure out what mix of inorganic components would get closest to 5-1-1. I'm leaning towards replacing the bark with pumice, peat with turface and perlite with DE.


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RE: 100% Synthetic Potting Mix?

That's kind of the thing, Jay. When you talk about the "(de)composition of the bark and peat" you are really saying that over time, 5-1-1 starts to look like my method. This is especially true for people who re-use 5-1-1 with additions.

To be frank, I don't get how "inorganic components would get (close) to 5-1-1"

You are really moving more to a manual/infrequent hydroponic system.

Which is fine. But maybe you should go all the way then, and run some drip.


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RE: 100% Synthetic Potting Mix?

Hey John, I'm not really sure what the method is you're advocating. I've grown in all kinds of organic mixes and they're great (like you said, maxing out tomatoes in full organic pots). And I still go organic in my 5-1-1 mix and it works fine, though I'll probably experiment with different fertilizer regimens. I don't think an inorganic mix is incompatible with organic nutrients. Aquaponics is an example, as is typical hydro where people use teas and culture mcyo and bacteria herds.

I just don't want my mix to break down over time. There's a bell curve of when the mix has the ideal water/air retention ratio. 5-1-1 and gritty have no nutrients, they're already a "manual/infrequent hydroponic system" just with a component that decomposes and mucks up how the mix performs. Why not replace the bark with something with similar properties that doesn't break down?


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RE: 100% Synthetic Potting Mix?

I don't actually advocate any one method. I'm just sensitive to suggestions that methods which do work for me "can't" or "don't" work. Or "shouldn't" be done.

Maybe I think compost users are "under-represented" as well. This is particularly odd because "(partially) composted pine bark" is sometimes "good" for 5-1-1.

In terms of what you are seeking, I think I understand, and I support your goals. I was serious though about the drip irrigation (and fertilizer injection).

If you want to go inorganic, wouldn't an automated watering system make that much easier?


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RE: 100% Synthetic Potting Mix?

I gotcha, and you're totally right about drip making it easier -- I now have my trees on drip and was looking at fertilizer injectors this morning, thinking about the Ez-Flo.


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RE: 100% Synthetic Potting Mix?

Cool. I sometimes think about the Ez-Flow, but right now my garden is way to small to justify it.


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RE: 100% Synthetic Potting Mix?

Using a more "inorganic approach" to container gardening would include avoiding organic fertilizers such as composted manures, fish emulsion, etc... and sticking with a liquid feeding program that balances NPK in the amounts I require... giving me control over what happens within that container, as it pertains to nutrition, moisture, etc.

But I still use fir bark as the main ingredient for my Gritty Mix, with gran-i-grit or turface and perlite as the balance of the medium. The fir bark I use is actually intended as bedding for reptiles... it's not already beginning to break down like some of the bagged pine barks I've seen used. I actually get a couple of years use out of a batch before I need to build more medium.

Some people use lava rock particles, pumice, akadama, crushed granite, or other ingredients in their mixes... I generally stick to fir bark, gran-i-grit or turface, and a coarse perlite... for extra moisture retention, I play around with a high quality potting mix or peat... adding just a little to obtain more moisture retention. It all depends on the plant, the pot size, where it will be located, etc... most of what I grow in containers remains indoors.

It's rather difficult to control what happens within a container when everything is organic. PH can quickly become an issue, and we don't have the same living army working to break down organic matter into usable food.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Thu, Jun 5, 14 at 16:07

If you are going to use a fertilizer injector, just save up for a dosatron. They are fantastic. Also know that if you use a fertilizer injector check local building codes to see how you have to plumb them to be legal. You will have to use some sort of backflow preventer like an anti-siphon or double check valve, and remember that anti-siphons have to be higher than all the emitters on the circuit to perform that function properly.


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RE: 100% Synthetic Potting Mix?

I think some might be over-generalizing the science on fungi and containers. It is certainly true that pots will have a more narrow microbiome than free soil, but scientists actually have to filter air (HFC) to keep them out of greenhouse experiments with containers:

Seedlings grown in the HFC had fewer mycorrhizal short roots than those grown in the open greenhouse atmosphere. Furthermore, the proportion of seedlings from the HFC that were completely non-mycorrhizal was higher than that of seedlings from the greenhouse atmosphere. Seedlings grown in sterilized, artificially based growth media (>50% peat moss, vermiculite, and/or perlite by volume) had fewer mycorrhizal short roots than those grown in sand- or soil-based media.

Reducing airborne ectomycorrhizal fungi and growing non-mycorrhizal loblolly pine (Pinus taeda L.) seedlings in a greenhouse

There seems to be a popular belief that containers are dead, when little in the natural or built world is really that way. The microbiome of the built environment is a hot topic right now.

(that last line about "fewer mycorrhizal short roots" might be worth noting as well.)


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RE: 100% Synthetic Potting Mix?

No, the belief isn't that containers are dead - the fact is that smaller containers (of the type used by many backyard gardeners) aren't conducive to maintaining herds of micro-organisms. With moisture and temperature fluctuations, those microbes go through boom and bust cycles. As such, it can be more difficult to fertilize, or rather predict fertility, if using organic nutrients in a smaller container (3 - 7 gallons).

Josh


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RE: 100% Synthetic Potting Mix?

That makes more sense, Josh. The words "herds" and "boom and bust" are certainly an evocative description. Not sure how I translate that into actual risk though.


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RE: 100% Synthetic Potting Mix?

The micro-organisms rapidly reproduce and colonize the potting mix when temperature and moisture are favorable; however, in the heat of day, those populations are reduced due to heat and diminishing moisture. If one attempts to fertilize when the population is low (in a "bust"), the fertilizer won't be broken down into useable form for the plant....so growth potential is limited until the population of microbes increases to the point where the organic nutrients are broken down in a form and quantity the plant can use.

The risk is to the wallet (inefficient use of fertilizer) and to growth potential. As always, if one is going to use organic methods, one should use larger containers or raised beds.

Josh


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RE: 100% Synthetic Potting Mix?

Hey Josh, great info on organics!

Any thoughts on an inorganic 5-1-1 mix? Or what could replace bark? I'm thinking some combo of pumice, turface, DE and perlite should do it.


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RE: 100% Synthetic Potting Mix?

From a minimalistic point of view the "soil" can be just about any materiel you wish it to be, as long as it contains moisture, oxygen, and food in the correct amounts and it provides some form of support for the roots and plant. Many types of inert, inorganic material would work. Depending on what materials you select you may have to water more frequently and fertilize more often than you would in a typical 5-1-1 mix but its certainly doable if you wish. I believe Al mentioned somewhere on here that he sometimes grows plants in 100% Turface.

The Missouri Gravel technique relies basically on just pea gravel and moisture/fertilizer I believe. No organic material at all as far as I know.

TYG


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RE: 100% Synthetic Potting Mix?

Hey Yard guy, totally agree, I'm trying to see if there's a way I can get close to the moisture retention of 5-1-1 but inorganically. Turface seems like it's a good replacement for peat. I'm thinking pumice, lava and/or DE is a good replacement for bark fines.


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RE: 100% Synthetic Potting Mix?

Jay,

If I recall correctly, I think I read that Al mentioned that DE (NAPA Floor Dry, OptiSorb, etc.) can be used as a substitute for Turface. I think they are more or less interchangeable. I think granite and perlite are also fairly interchangeable. I've never used pumice or lava rock (not very easy to come by that stuff in Michigan lol) but I've also heard good things about them.

This doesn't answer your question at all, but I think I also recall reading on here somewhere that fir bark lasts quite a bit longer in soil mixes than pine bark. Takes much longer to break down. Since you are on the West Coast you might find fir bark easier to come across then pine bark. That of course has nothing to do with inorganic, just mentioning that in case you are interested.

TYG


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RE: 100% Synthetic Potting Mix?

If you grow in straight turface, you will have far more moisture retention than the 511 mix. I see no point in using both turface and DE in the same mix, as they are close to the same thing. I wouldn't really say turface is a replacement for peat, as they are totally different things. You could say that turface holds a good deal of water, grit holds just above none at all, and bark draws the line down the middle. That about sums up gritty mix. With that said, you can easily see how one could alter the moisture retention by adding or subtracting ingredients. You simply change the ratio of your moisture holding ingredients (turface, DE), and your non-moisture holding ingredients (grit, perlite).

All in all, you may have to approach this from a different angle. Rather than trying to "find a replacement" for the 511 mix ingredients, just look at creating an inorganic mix that fulfills your needs. If you just settle on what you feel is a good replacement for the bark and peat, then mix them up at 511 ratios, you'll have a mix that doesn't even resemble the original 511 mix. I think you gotta knock down this mountain you've created, and bring it back to mole hill status. Focus on creating an inorganic gritty mix with some of the above mentioned ingredients in this thread, water and fertilize properly, and see how it goes. If you feel it's not holding enough moisture, or it's too wet, make adjustments. The answer will eventually come to you, but not overnight.

Joe


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RE: 100% Synthetic Potting Mix?

I'm afraid Josh, that isn't really making sense to me. I do have a chemistry background, so maybe you can help me get there.

The visuals of "micro herds" thundering in pots is strong, but I'm not sure it is really the way soil communities work.

In particular, you are making the argument that one high organic matter system (5-1-1, 86% OM) will retain stable microenvironments through the day, while another high OM mix (say 50-80% compost) will go wild.

Is that science, or is that visualization?

(ha, spell check changed microenvironments to microcomputers. fixed.)

This post was edited by johns.coastal.patio on Thu, Jun 5, 14 at 22:14


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RE: 100% Synthetic Potting Mix?

(I suspect that rapid, wild changes, are things that people say, rather than things that have been documented, in hard chemistry of the soil.)

Update: I found Issues with compost in potting mix in a University of Vermont Extension document. "Boom and bust" is not one of them.

Like anything it's not nirvana, but for people used to choosing just the right pine fines, other people looking for good compost should not be surprising.

This post was edited by johns.coastal.patio on Thu, Jun 5, 14 at 22:37


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RE: 100% Synthetic Potting Mix?

Re: inorganic mixes, I think quite a few folks are using 2 parts non-porous grit and 1 part Turface. DE is a great sub for Turface...in fact, it has a slightly better CEC, and holds a little more moisture per weight. Perlite holds a LOT more moisture than granite, though, so don't use those interchangeably.

John, I'm not really sure what you're asking here:
"In particular, you are making the argument that one high organic matter system (5-1-1, 86% OM) will retain stable microenvironments through the day, while another high OM mix (say 50-80% compost) will go wild."

What I'm saying is that using a synthetic fertilizer doesn't require micro-organism "herds" to cleave hydrocarbon chains and reduce organic nutrients to elemental form...because the synthetic is already in a form useable to the plant.

5-1-1 is every bit as susceptible to overheating and drying out if used in smaller containers, and so the micro-organisms will be going through "boom and bust" cycles as they would in similar organic mixes of the same volume.

Josh


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RE: 100% Synthetic Potting Mix?

It's just that you set up this great vsiual, Josh. It had herds thundering, spooked by lightening, heading for the metaphorical cliff ... maybe Bruce Dern in there somewhere.

I've shown that the University of Vermont doesn't worry about that.

So now you've moved to "need to cleave."

New goalposts, and presumabley ones now where you think the "organic" mixture is never fed MiracleGro?

For what it's worth, I use compost in my medium and MiracleGro (clone) too. In terms of "efficiency" for my small garden, my $4 on-sale purchase should last me 3-4 years.

Someone probably could do it with a compost based mix and then organic fertilizers, but it is not my goal right now.


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RE: 100% Synthetic Potting Mix?

Thanks Josh, that's helpful -- so it sounds like DE over turface. Does pumice fit in somewhere? I'd really like to stay away from grit, it's just too heavy for my 15 gal pots. Maybe a combination of pumice, DE and perlite?

Also, is there an upper limit to water retention while still providing the necessary oxygen exchange? My dream mix would hold the water of a peat-based mix with the long term performance of gritty.

Joe: you're right, I'll probably have to do some tests. But I'm already spending way too much time on this hobby, I guess that goes with the territory :)

This post was edited by Jay-Part-Shade on Thu, Jun 5, 14 at 23:29


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RE: 100% Synthetic Potting Mix?

Sorry to derail as far as I have, Jay.

I guess it's crazy to me that I can say something as open as this:

The constellation of potting mixes is very large. At the other extreme from synthetic mixes, we have whole families of organic and permaculture styles.

As I've said, I think the fact that all these styles are used by commercial growers means that they can and do work, and provide useful ROI.

There are commercial growers of greenhouse crops using synthetic mixes, and people using compost as well.

Whatever your interest, you can probably find a model that works.

Then, after that, I have to defend things that work.

Defending what works for me is not actually attacking what works for you.


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RE: 100% Synthetic Potting Mix?

Hey John, I don't think anyone is disagreeing with you, I know I'm not. I love compost and full organics. My goal here is to find a mix for my trees that never breaks down. Whether or not it performs better with synthetic or organic fertilizers is a completely separate issue.


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RE: 100% Synthetic Potting Mix?

John, I haven't moved the goal-posts in the slightest, and it irks me honestly that you would throw that rhetoric at me. I've attempted to address two key elements of the organic conundrum and why many folks seek an inorganic mix. The first is the issue of drainage and aeration; the second is the issue of fertilization efficiency. Drainage and aeration has been covered satisfactorily already, so I posted on the particulars of organic and synthetic nutrient efficacy.

I tried to be very specific for you regarding the two distinct issues that are tied to smaller volumes of mix, organic or otherwise.

I'm certainly not telling you to change your methods; I'm merely suggesting that one can perhaps coax more from their gardening experience by anticipating the likely Limitations of an organic mix fed with organic fertilizers.

Josh


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RE: 100% Synthetic Potting Mix?

Josh, you are making "the bumblebee can't fly arguments."

And you think those arguments trump all the flying bumblebees in the world.

I guess this is the way of the internet. There can be 1001 commercial growers out there with a compost based mix, but on a back thread in some forum some guy can argue that it is all impossible.

(And you certainly discarded the whole "boom and bust" thing when I gave you the University of Vermont concerns, to name some more things that are not University of Vermont concerns.)

I think it was pretty up-front of me to link to that, the actual concerns that actual growers acknowledge, and work around.

UMassAmherst: Organic Growing Media and Fertilizers for Greenhouses

That also does not speak of "boom or bust" or difficulties cleaving hydrocarbon chains.

This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 1:04


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RE: 100% Synthetic Potting Mix?

Wrong, John, absolutely wrong.

More of your insulting rhetoric...instead of goal-posts, you've saddled yourself a bumblebee this time.

Where have I written that organic gardening is impossible? I've written of the inefficiency and the unpredictability (not the outright impossibility) of using organic fertilizers in smaller volumes of mix. And I've been writing the same thing for several years now. Take note of what I wrote most lately: "I'm merely suggesting that one can perhaps coax more from their gardening experience by anticipating the likely Limitations of an organic mix fed with organic fertilizers." That's a diplomatic way of saying that While one might be satisfied with their current level of success, a greater level of success might be achieved by working to reduce the Limitations of a particular method.

I certainly did not discard the whole "boom and bust" thing. Where on earth did you misread that? I shall quote myself for you, where I repeated exactly what I wrote before: "What I'm saying is that using a synthetic fertilizer doesn't require micro-organism "herds" to cleave hydrocarbon chains and reduce organic nutrients to elemental form...because the synthetic is already in a form useable to the plant.

5-1-1 is every bit as susceptible to overheating and drying out if used in smaller containers, and so the micro-organisms will be going through "boom and bust" cycles as they would in similar organic mixes of the same volume."

Doesn't seem so hard to understand. Perhaps you are being intentionally obtuse in order to argue and insult those who thought you were interested in an actual discussion.

Josh


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RE: 100% Synthetic Potting Mix?

Ok, forget the organics and compost, that's another thread.
Jay, have you ever considered that the bark isn't going to break down as much as you think it is in the time period that the plant is going to be in that container before it needs to be repotted? I just repotted a plumeria that was in a little pot for over three years and I don't think the bark broke down at all. The plant was just about root bound and the mix looked like I just put it together. I really think you'll be repotting before that bark gives you trouble, and how many years would it take before it came close to the texture of peat? I think a little fir bark is good for the critters.


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RE: 100% Synthetic Potting Mix?

"I've attempted to address two key elements of the organic conundrum and why many folks seek an inorganic mix. The first is the issue of drainage and aeration; the second is the issue of fertilization efficiency. Drainage and aeration has been covered satisfactorily already, so I posted on the particulars of organic and synthetic nutrient efficacy."

This is what I was worried about when using organic mixes. But I have found adding compost is not really a problem as far as drainage and aeration. I found this to be kind of a myth really. Compost holds moisture like peat does, and to be technical peat is compost. So cut the peat add compost, as it is virtually the same thing. All these years you have been adding compost to your mixes. That is if you use peat. I also discovered that using DE over perlite increases aeration, but does add more water retention. Which I have found useful, as it tends to be like a moisture control sopping up excess water. Also because the pore size is larger than turface, water in DE is a lot more available to the plants, as noted in numerous studies. My pots are in the open, and it often rains a lot, DE I have found to be very useful.

I'm not really interested in being organic. I'm interested in the best environment for my plants. So I agree about the fertilizer efficiency. I like to use organics as nutrition is always there, and there when the plants need it. But at times I need quick adjustments, so I use both chemical and organic fertilizers. I have found this approach to work extremely well.I'm in zone 6 and I'll be harvesting tomatoes from my 3-4 foot plants in about a week. Not a bad size for zone 6 at the start of June.

I have stated as such a thousand times on this forum, but people see, and read what they want to and ignore the obvious. Not much I can do about that.

As far as a good synthetic mix for trees, that interests me somewhat, but I want it for cacti which I don't transplant very often, hence the need for a long lasting mix.
I have observed that bark breaking down before I transplant as not a problem as long as it is fast draining.
The drainage slows, but not by enough to matter. One just has to be careful about watering. I don't leave my cacti in the open. An overhanging porch protects them from rainfall.
I also use clay pots, and you can have just compost in clay and it will dry quickly, again ways to adjust for the water retention of compost, very easy to adjust for it. And I feel the benefits of a living media out way the few easily overcome disadvantages. The new cloth pots are very much like clay pots. This makes using compost that much easier.
No doubt the trend is moving away from soilless mixes. It's a good thing it is taught here how to make them, as soon buying them will be difficult.


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RE: 100% Synthetic Potting Mix?

I'd like to just add that if commercial growers are to be brought into the discussion, it should be noted that commercial growers have one goal: profit. The long term health of what they grow is not their priority, making money is. That means they'll choose the most economical materials and methods possible, which means they aren't going to spend extra money on things like high quality pots or anything, and certainly not on potting mix material. Not to mention the labor it takes to sift such material, and the more frequent watering and fertilizing required.

Joe


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RE: 100% Synthetic Potting Mix?

JERRY: You're possibly right about bark not breaking down over 3+ years. My issue with bark has been more about the quality coming out of the bag (all over the place) and what I perceive as a bell curve of performance. It starts off not quite ideal, breaks down a little bit and works really well then breaks down too much. Out of my 50 or so plants, I can see some where the mix just isn't performing as well and I think that comes down to the massive different qualities of bark I've gotten.

Also, this is more of a thought experiment -- if 5-1-1 and gritty are designed to prevent compaction and not break down like peat-based mixes, why not go all the way? Is there something that inherently doesn't work in an all inorganic mix for long term plant growth? I just don't know.

DREW: Not to get back to the organics argument, but it's worth noting that I've found single crop plants like tomatoes are fine for peat, compost, etc. and perform better than 5-1-1 in my experience. I've got cucumbers and some tomatoes in peat and compost right now and they're doing great. But from previous years I know the mix will only last 6 months at most before it becomes a near solid block of concrete. This year, I'll try to keep my veggies in the 5-1-1 going through the winter (this being LA and all).

My goals are growing rare fruit trees long term in big pots and slow growing succulents and cacti. I'm not really worried about my veggies, seeds are cheap and tomatoes are practically a weed :)

JOE: You bring up an interesting point and I do wonder about commercial growers. Out of the few dozen trees I've purchased, about half come in a bark-based mix and the other come in a massively heavy granite mix. That said, those growers are growing to a certain point before selling them (usually after 2 years), and not really concerned about making sure the mix stays stable beyond that. I'm not sure there's any commercial tree growers that are growing for long term fruit production rather than selling the trees. If there are, I'd be really curious to know what they do.


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RE: 100% Synthetic Potting Mix?

Jay I don't have the problem with bark that you seem to find, it's probably because I buy E.B. Stone Orchid Bark, it's fir and it's really a nice bark, it holds up for the long haul. I do a gritty version and I leave my plants go for a while before repotting, so that's why my choice of bark was important.

Jerry


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RE: 100% Synthetic Potting Mix?

Josh, do you have anything more than metaphor?

Seriously, you tell these stories, and I return with university extension papers, and you tell more stories.

I'd like to just add that if commercial growers are to be brought into the discussion, it should be noted that commercial growers have one goal: profit. The long term health of what they grow is not their priority, making money is.

That sir, is a classic example of confirmation bias in action.

Think of a reason to wave away actual results with positive ROI, even by suggesting that ROI is a bad thing.

I spent $0 out of pocket for my potting soil (for tomatoes) this year, and my tomatoes are 6-7 feet tall.

I call that ROI, and not a bad thing.

This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 11:31


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RE: 100% Synthetic Potting Mix?

Josh, seriously, if you want to say this to a scientist:

"I've written of the inefficiency and the unpredictability (not the outright impossibility) of using organic fertilizers in smaller volumes of mix."

You need a study. Not a story.

And, if there really is "inefficiency and the unpredictability" it will show up as poor ROI for organic growers, small and large.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jun 6, 14 at 11:48

I feel the need to add that most wholesale growers use a lot of CRF and fertigation. The media they use is generally built around partially composted bark. This is because partially composted bark has better water retention than fresh bark. Fresh bark lasts longer, but since they repot every season that is not a concern.


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RE: 100% Synthetic Potting Mix?

Here is the University of Connecticut on fertilizing houseplants:

The fertilizer label will also state from what sources these nutrients are derived; chemical and/or organic. If synthetic or chemical fertilizers contain trace elements, these too will be listed on the label. Trace elements or micronutrients are needed by plants in very small amounts and include iron, boron, zinc, copper, molybdenum, chlorine and manganese. It is usually safe to assume that organically derived fertilizers, because of their nature, contain some or all of the necessary micronutrients. Potting mixes that have a mineral soil component may also supply sufficient amounts of micronutrients. If you are not using an organic houseplant fertilizer, consider purchasing a chemical fertilizer that does include micronutrients since they are typically not present in soilless potting mixes.

See if you can find a word on your worries in that paper, Josh.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jun 6, 14 at 11:52

Jay, your dream about a completely inorganic medium with thesame properties as peat based media is completely quixotic. Give it up and just deal with watering frequency by installing an irrigation system.


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RE: 100% Synthetic Potting Mix?

John: all interesting info, but can we keep this thread on topic? Your points regarding organic fertilizers and mixes would probably be best suited for a new thread :)


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RE: 100% Synthetic Potting Mix?

I know nil13, and I think those methods are a good model for space-intensive gardening. They come in more conventional and organic certified variations.

Which we choose can be based on our general preferences, but also our local costs.


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RE: 100% Synthetic Potting Mix?

Ok Jay.

I tried to just hold the line at "all these things work," but again that took some "defense."

Here it is: Big Tent Container Gardening

This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 12:22


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RE: 100% Synthetic Potting Mix?

John, I can see you like to argue with people on the internet, and like to put words into people's mouths or make assumptions about views and intent. You assume I am complaining about commercial growers and their ROI, and that I think ROI/profit is a bad thing. You are dead wrong. I merely stated that commercial growers' number one goal is profit, and there is no argument you can make against that. Do they want to provide other things like quality products too? Sure. But, profit still trumps that. But, you've now transformed this thread into a heated argument with personal attacks, so its time for me to move on.

Jay, I hope you find what you're looking for, and good luck in your growing.

Joe


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RE: 100% Synthetic Potting Mix?

"Do they want to provide other things like quality products too? Sure. But, profit still trumps that. "

I disagree, without quality, one will be without profit.
At least in the long run. Such bad business practices will result in failure eventually.
Like GM trying to save money by not recalling a part,. Did that work? Did they save money?


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RE: 100% Synthetic Potting Mix?

The important thing to understand, Joe, is that I am defending everyone's right to find their own path.

People come back with reasons to disdain one or another successful method.

If you really want to do that, bring it to the new thread.


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RE: 100% Synthetic Potting Mix?

Using uncomposted bark, I find that bark-based mixes can go approximately 3 years, and then the breakdown becomes quite obvious (and has a definite effect on drainage and aeration). I've documented some slightly different bark-based mixes after 2 - 3 years.

In this first mix, wherein I grew my Avocado for 2 years, the breakdown was less noticeable due to the significant inclusion of various grit - perlite, pumice, scoria, turface, and some quartzite.

Josh


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RE: 100% Synthetic Potting Mix?

In this second mix - bark, perlite, and scoria (red lava rock) - the breakdown was much more apparent in the same 2 year time-frame. This mix is what I used for my Giant Chainfern (outdoors in a large container year-round). I fertilized with Fish Emulsion solely, watered much more often (due to the plant being a fern), and the container received Winter rain. Notice also that the mix was colonized by moss due to the favorable conditions created by the fern. These factors together contribute to the decomposition of the bark in the mix.

Josh


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RE: 100% Synthetic Potting Mix?

Thanks Josh, that's really helpful!

If you were to try mixing an inorganic mix (without grit, too heavy for me), what would you try? Would some combination of pumice, DE and perlite work? When potting up, it'd be great not to have to shake out the mix from the roots. Unless I'm missing something, is there any real reason why there has to be an organic component in the mix?


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RE: 100% Synthetic Potting Mix?

Thanks, Jay.
The bark just happens to be an excellent filler (durable, economical, fairly light-weight, favorable pH, favorable moisture retention curve).

Your question about creating an inorganic mix is a bit more difficult due to the moisture retention of each of those three ingredients. The function of the non-porous grit (granite, quartzite) is to adjust down the moisture, which is very helpful...but also quite heavy.

I have some succulents (Jades) in pure Turface, and some in pure scoria (red and grey lava rock), but I'm not sure how well that would translate to larger containers and different plant species.

If you have access to large coarse Perlite, you might be able to displace enough moisture to make a mix of pumice and Perlite work.

Josh


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jun 6, 14 at 21:18

Josh, I bet if you dug down to the bottom of those containers it would look even more decomposed.

I should have taken pics of some of the grasses I just split up that were in 1s. The pots were only 1/4 full and the media that was left looked exactly like worm castings.

Jay, are you thinking about adding perlite for weight? Also, if you do use perlite don't get the thermorock crap they have most places, too mny fines. You need the sifted large horticultural grade stuff.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Fri, Jun 6, 14 at 21:23

Jay, if your problem with bark is consistency, just start buying orchiata or the cheaper good stuff the orchid folks use. You miht want to check out Yamada Co. Down in Gardena.


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RE: 100% Synthetic Potting Mix?

Indeed, Nil, the lower layers are much more evenly broken down. Thankfully, the mix doesn't compact much and so the potting mix *level* doesn't sink as much as other mixes do.

Josh


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RE: 100% Synthetic Potting Mix?

Josh, great info, it sounds like I'll probably need to experiment to get the right ratios. I'm not worried about replacing the grit, more like finding something (or a mix of something) that comes close to mimicking the bark in 5-1-1. And I'm growing in 15 gal bags, all fruit trees, mostly sub tropicals, so it seems like I should try to find something that fits their needs. My biggest concern are my avocados, I have six now, a couple rare ones, and I really want to keep those guys happy.

Nil, you're right, I've gone through tons of bags of the cheap crap and it's like I'm inhaling fines. The hydro store in Atwater (Atwater Hydro) has both the medium and huge size perlite for a reasonable price (I think $15-20 for a 3cuft bag). I've found Greenall Microbark from Armstrong on San Fernando is really excellent quality, but it's $10/bag to Home Depot's $4 so it pains me to spend that much filling up the truck since everything at Armstrong is so damn overpriced. I mean, $50 for a 5 gal mission fig? They're out of their minds.


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RE: 100% Synthetic Potting Mix?

Ah, the Avocado....touchy plants in containers up here. I hate doing any root-work on mine, which is why I've kept it in the same mix for several years now. The last mix change that I did, I used a mix of screened fir bark (Greenall), red lava rock, and turface. I flood the mix these days and use a drip-tray because the poor tree is so root-bound and wilts if not watered every other day or so.

Josh


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RE: 100% Synthetic Potting Mix?

Here's a shot of the Avocado mix....
Fir bark, scoria, turface.

Josh


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Sat, Jun 7, 14 at 12:26

Well Yamada has 4 cuft bags of perlite for about $10, and 2 cuft bags of orchid seedling bark for $9. The best part is they have 50# bags of Nutricote 180 for about $70.

This post was edited by nil13 on Sat, Jun 7, 14 at 12:40


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RE: 100% Synthetic Potting Mix?

One thing that I wonder, Jay, is if the wicking properties of the fabric pots will offset, at least to some extent, the compaction/breakdown of your potting media over time. Yes, the organic components (bark, peat, etc.) will break down into ever smaller particles, but, since fabric pots are less likely to support a perched water table when in direct contact with soil, does that really matter? With that question in mind, I've begun using a modified 5-1-1 recipe for all of my plants in fabric pots (degradable Root Pouches) that's five parts aged bark fines, 2 parts fine material (peat, compost, etc.), and 1/2 part each coarse perlite and D.E. My hope is that this mix will do a better job of retaining moisture while the fabric pots will help to maintain sufficient aeration for healthy root growth. I'm planning to leave the plants in these pots for at least 2-3 years before changing out the mix, so perhaps we can compare notes in a couple of years.


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RE: 100% Synthetic Potting Mix?

JOSH: Good to know about the avocado, I'm betting that it actually loves being flooded that often, given how they love drainage and they're grown commercially on hills. I didn't bare root my first avocado (a sir prize). It was in a decomposed granite mix that drained really well, so I just knocked a bunch of dirt off and stuck it in. It's been growing pretty well, but I'm worried I might want to bare root it to a more consistent mix. My Jan Boyce was bare rooted and nearly died, lost all but one sad leaf and half its branch tips turned black. But now it's flushing out all new growth. The Mexicola and Lamb Hass laughed at being bare rooted and acted like nothing happened, Mexicola especially, the thing is indestructible, and the lamb hass kept holding fruit (that I've since removed). I also have a Hass and Kona Sarwil that complained a little but were otherwise fine with bare rooting. And all this was right before the crazy heat wave and fire storm down here.

NIL: WOW, fantastic resource. I didn't know about Nutricote before but their product line is impressive -- I need to make a field trip to Yamada. It's the one in Gardena, right?

SHAZAAM: Interesting ideas, the bags are definitely big on wicking and air exchange. None of my bags are touching the earth, they're all on my patio, driveway or elsewhere. I imagine if I put them on bare dirt, they'd act like a raised bed and one could get away with almost any mix. In fact, if I were doing that, I'd do a raised bed mix to encourage more worms and things to till the bed (I did that last year with a peat-mix in 10 and 15 gal bags and it worked great, tons of worms and growth). I just calculated how many gallons of 5-1-1 I've made. It's around 350 -- 20 15-gal bags and the rest 7 and 3 gal. I wanted to stick the basic recipe before going off the reservation, but, yes, let's compare notes. The more I read about DE, the more I think it's a great addition.


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RE: 100% Synthetic Potting Mix?

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Sat, Jun 7, 14 at 14:09

Yeah it's in Gardena.

If you find a good source for big DE in LA let us know. You should know though that you can get Turface just down the street at Ewing on Colorado.


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RE: 100% Synthetic Potting Mix?

Jay, each time I re-potted my Avocado, it lost all the older leaves, keeping only a few top leaves. Then I finally got smart....and I put the thing in deep shade after re-potting, and I watered the new mix every day to keep the *upper* inches moist. That really cut down on the leaf loss. Now it's a monster, and still in that tiny clay pot. It's developed a lean, though, so I'll have to prune it pretty hard.

Josh


 o
RE: 100% Synthetic Potting Mix?

NIL: Good to know about the Turface and I've been looking for a source of Axis without success, their website makes finding it near impossible. I'm thinking I'll start with Optidry from Oreilly just to experiment before filling up the truck.

JOSH: Nice looking avocado -- those are probably the biggest leaves I've ever seen! Grown from seed, I assume? What was the donor fruit (Hass?)? Are you planning on growing it to fruit? Or grafting? Or just decorative?

Yeah, I stuck all my trees inside after repotting them during the heatwave and usually keep everything else in shade for at least a couple of weeks. The handles on the bags and a small dolly make it easy to move. Also, I do the bark mulch on top since avocados have a lot of surface roots. But I don't think you have any weak root issues :)


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RE: 100% Synthetic Potting Mix?

Hehe :-)
I'm growing this one decoratively...it's about 4.5 year's old from seed. I can't remember what the donor fruit was (probably a Hass as they're popular up here). The seedling popped up in my garden, so I dug it up in November and have been Wintering it indoors ever since. I prune it a couple times per season in an attempt to keep it compact, bushy, and with multiple branches to its canopy. It really loves sun, water, and fertilizer....but you know all that!

Josh


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