Yogas
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Square foot garden mix

I just finished building my first square foot garden and I am quite proud of it! Mel Bartholemew suggests a mix of 1/3 peat moss, 1/3 vermiculite and 1/3 compost. Here's my question - would that be a good mix to use in containers also? I have some Topsy Turveys and I also just built 2 Earthtainers. It seems like this mix is light and would do well. Anyone have any opinions or advice?

Thanks! :D

cynthia_h
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I now have five raised beds for my veggies. The first one was filled according to The Word of Mel Bartholomew. :wink: But it was a real challenge to get the growing medium wet: all that peat moss resisted getting wet with all its might. :x

So...never again. Three of the other boxes were filled with a combination of my own compost, various purchased composts (e.g., grape pomace, and a mixed-source compost from a landscaping company), vermiculite (Freecycle!), and some potting soil in big bags.

The fifth box, DH decided *he* didn't want to wait for potting soil...he had a wheelbarrow or so full of native soil we had taken out for grading purposes, so he thought, "Well, that needs filling, and I've got dirt here...." See where I'm going, yes?

And that fifth raised bed, which he filled with native soil in Summer 2008, STILL has weeds in it because of the weed seeds it contained. :x The other four beds only sprout weeds occasionally, probably due to squirrel/bird distribution.

In less developed areas of the world, Mel recommends 100% composts built from the materials the gardeners/small-plot farmers have on hand. It can be dicey, trying to grow in 100% compost, but his recommendation does show that the peat moss is optional. I like the vermiculite; it's still out there in my (four) boxes, helping out with drainage and lightness of texture. :)

Cynthia H.
Sunset Zone 17, USDA Zone 9

bogydave
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I have been using 100% home made compost for 2 years. Garden does well.
I've put 1/2 done compost (moldy leaves & stuff) on the bottom & covered with a 50/50 mix of HorseManure & garden compost. It does well.
I've mixed 50% HM compost with 50% garden compost & did well.
100% HM compost did well but doesn't hold moisture as well (had to water more)
100% garden compost did well.
I did learn to walk down the compost to tighten it up so it holds moisture better, but am happy with the results now , 2 years so far.
Every year I just add fresh compost to the top & mix it in a bit. Soil level seems to shrink so adding compost keeps them full.
Even have worms in the beds now, eggs I guess from the compost bins.
I like the consistency of the 50/50 mix best for moisture retention & drainage.
The straight HM compost dried out pretty quick the first try, so I compacted it with my fist around the plants & added to it. "Learning cure" thing.

In my area , usually not allot of rain until mid August so moisture retention is important. If I were in a wet area, perlite may be needed.
Really dry area, some peat & compacting it some would help.

My idea is to experiment & see what works best.
All my 100% home made compost mixes worked, ( once I learned to compact it) Cheaper too. :)
"

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Kisal
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I dislike peat moss, so if I were creating my own mix, I'd probably start with compost and then add an equal volume made up of a mixture of worm castings, a good portion of perlite, maybe some coarse sand or fine gravel (I'm fond of the fine gravel sold for aquariums, which has grains between 1/16 and 1/8" in diameter), and some leaf mold.

You mention that you want to use your mix in containers, and for that, I consider the perlite (I have a dislike for vermiculite that almost equals my dislike for peat moss ... :lol: ) and coarse sand/fine gravel are absolutely vital. Don't stint on them.

I have a hard time classifying raised garden beds as "containers". (The exception would be very small raised beds, no more than 3' on a side.) The reason for that is that, to me, a container, i.e. flower pot or planter, has an attached bottom, the presence of which seriously restricts drainage. The majority of raised garden beds do not have closed bottoms, but are just a frame of sides set on the ground. Even raised beds placed on a solid surface, such as a concrete patio, have less restricted drainage than a pot with a few holes in the bottom. But that's just my own point of view, and it's fine with me that not everyone shares it. The gist of this paragraph is that a soil mix destined for use in planter with an attached bottom must provide excellent drainage, whereas a mix destined for use in a large raised bed with an open bottom can get away with being a bit heavier. For that reason, I stress the necessity of adding plenty of perlite, along with some fine gravel to mixes destined for use in containers. JMO. :)
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams

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Duh_Vinci
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I agree with all above said, specially keeping the moisture during the hot summers - his mix doesn't do well in that respect.

I too add more home made compost, but what I found that works the best, is adding about 1/4 top soil and 1/4 of native clay to the mix... Moisture retention is amazing.

As for using the same mix for containers - there are numerous recipes, some work better in some climate, some better in others. Personally, I think it's a good mix to start with, but too fine, by the end of the season, this mix will get too compacted. Adding 1/3 of pine bark fines:

[img]https://drphotography.smugmug.com/photos/1242491225_7gDN7-O.jpg[/img]

This adds enough coarseness to the mix where roots can freely grow well and enough air space between the particles to have an adequate oxygen levels for the roots to breath. So the final mix looks kinda like this consistency:

[img]https://drphotography.smugmug.com/photos/1242538769_YjwQK-O.jpg[/img]

Good luck!

Regards,
D

Yogas
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Location: Chicago

Kisal

Why do you dislike vermiculite and peat moss? I'm learning so much I want everyone's opinions.

I did end up adding more compost to the mix and a worker at my local nursery did mention using the bark fines (thanks Duh_Vinci)!

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Kisal
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Over the years, I found that they both tended to keep the soil too wet, not allowing it to drain freely enough. Perlite also holds water, but it isn't so soft. It seems to loosen the soil more, enhancing drainage, and because of its solidity, the soil doesn't compact so easily. Vermiculite always impressed me as being similar to little pellets of soggy cardboard, not really contributing much to improving the soil. It smooshes easily, so doesn't really help keep a soil light and fluffy.

In addition to staying wet too long, and refusing to absorb water if it once dries out, peat moss makes soil more acidic. Most plants like soil that's neutral or only slightly acidic, and desert cacti actually prefer soil that's slightly on the alkaline side. Most packaged mixes contain far too much peat moss, IMO. That makes them too acidic for many plants, and also inhibits free draining of water.

Lots of peat moss is fine in a soil mixture used to grow plants that really love acid soil, like azaleas or blueberry bushes. And it's fine in small amounts in all soils. I just think it's grossly overused.

There is other organic material that can be used to lighten soils, which don't add to the acidity or hold too much water. Coir is interesting to me, and I intend to do some experimenting with it soon as a container-mix component. I think it will enhance the texture of the soil, without keeping it wet overly long, or making it too acidic. I hope to play around with it this summer. :)
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams

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