Potting Soil

[Keiththibodeaux]

I ran across this in another forum. It seems interesting, so I am sharing it. I may give it a try as well. - keith

"Interesting excert from a newsletter at work today, thought I'd share. From a leading organic manufacturer.

"Potting soil should be light weight, but I do not recommend peat moss potting soils. Peat moss is anti-microbial. Microbes don’t grow well in it. That’s just the opposite of what we want. Peat moss is excellent for storing bulbs and potatoes, or shipping food or other perishable material that would otherwise decay. Potting soil should not be sterile. It should be alive and dynamic. It should be light, loose, well aerated, fertile, full of microorganisms and have the ability to stimulate quick and sustained microbiotic and vegetative growth.

My recommendations for a specific formula have varied through the years, but the latest recommended formula* is a follows:
60% Compost (compost, humate, coconut fiber, coir, earthworm castings, coffee grounds, etc.)
30% Rock (lava sand, natural diatomaceous earth (DE), zeolite, granite, etc.)
10% Sugar (corn meal, dry molasses, wheat meal, etc.)
*This mixture is not available commercially. Hopefully it will be sometime soon. For the time being, you'll have to make it yourself.

Other amendments that are beneficial in small amounts include greensand, beneficial microbes (bacteria and fungi) and organic fertilizers. For fertilization use fish meal, kelp meal and alfalfa meal."

[Gardenkeep]

So does this person think they can go to the local "I wanna be a gardener store" and actually buy a bale of peat moss that is sterile? There is nothing sterile in this world. The only reason they say some growing medium is sterile is to let the buyer know he's starting from somewhat zero and not getting some culture growing under junior samples pickup. This mixture you have transcribed is a recipe for muck depending on the age of the compost (tried this recipe about forty years ago) one last thought on peat moss. Scientists don't have a clue about its properties. Just a few years ago they said mushrooms were nutritionally useless and not until a few monks from Tibet pinned back their ears for them.

[mdvpc]

I think what Howard Garrett is saying (looks like his formula) is that peat moss isnt the right ingredient to support microbial life, not that it is sterile. That said, i have never used his formula, and agree that it is to heavy on compost If he is talking about compost. Sounds like he may be saying compost and other organic matter. It seems a little confusing. The most compost I have personally ever used is 25%.

[creister]

That sounds like Howards description for not using peat, but his latest recommedations are for about 40% coir fiber, 20% expanded shale, 20% compost, and the other 20% a mixture of greensand, lava sand and one other element.

I have used this in selfwatering containers, and did n't work well for me, but I have had better success in using raised beds, don't ask me why. I put what I had of this mix into a raised bed, and it grows stuff amazingingly well. But you all are right, that is too much compost for a mix.

[Gardenkeep]

Well since you're doing the thinking. what do you mean by"peat moss isnt the right ingredient to support microbial life" if by that you mean feed? We don't know that.
Peat moss is a soil/mix conditioner never sold as a fertilizer plant food or microbe nutrient feed, it has a perfect architecture for sustaining root structure. It's used for sustaining plant life.
There was nothing confusing to me about this article and others along the same tome, I found it quite amusing. I mean really you grow plants in broken Styrofoam as long as it's getting what it needs.

[Keiththibodeaux]

http://www.youtube.com/watch?v=aPLL1si-5Ds

[Gardenkeep]

If only I didn't have dialup

[fortyonenorth]

Being acidic, spaghnum peat alone will provide a good environment for soil fungi (beneficial and otherwise), whereas more neutral substrates will promote soil bacteria (beneficial and otherwise). As one component of a pH-adjusted potting mix, I think peat is ideal. I like that it's pretty consistent regardless of where you buy it. "Compost" is a wild card - unless you're making compost under controlled conditions with consistent ingredients, every batch will be different - sometimes dramatically so, i.e. garbage/gold in, garbage/gold out.

[Gardenkeep]

Excellent advice 41N, the only compost one should use is home grown.

[Stepheninky]

Originally Posted by Keiththibodeaux

http://www.youtube.com/watch?v=aPLL1si-5Ds

From the potting mix he shows I would assume his definition of compost is finished compost which truth be told is broke down to the point it could be used as soil. Anyways that's just IMHO.

As for microbes etc I would say the best base for a potting soil mix would be Fir bark

So just making this up off the top of my head as I am considering trying some formula of it next year.

50 % fine or medium fir bark (medium Fir bark to me is an option as its pretty cheap and fir bark breaks down very quick in warm and humid climates such as mine)

30% of a finished compost

10% sand or rock dust

5% perlite or expanded clay

5% char or fireplace ash

To this you would still want to add lime and a a good time release fertilizer.

Anyways the proportions might need some adjustment above but just trying to give you an ideal of what I am thinking.

I have seen fir bark used at 80% and mixed with ash as Orchid potting mix before.

and I have used Fir bark plugs to start seeds in with better results then using peat based mixes.