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Joined: Mon Jun 01, 2015 1:53 pm
Location: Hartford Connecticut (Zone 6A)

Earthworms & microbes and nutrients in my SFG.

The soil in my area is really bad clay like material and when we first moved here I had a hard time growing anything. I've spent the past 5 years, and a considerable amount of money adding organic material to my gardens and basically raising all the beds up so they are all now awesome.

Anyhow, my SFG has about a foot of gravel under it, then six inches of really nice clean topsoil inside of a huge 16’ x 19’ box. Over the topsoil I put landscape fabric, and on top of that I put my SFG boxes of various sizes (with more fabric stapled to the bottom of each) and filled them with 1/3 peat, 1/3 vermiculite, and 1/3 of compost that I bought at Agway with like ten ingredients in it.

So right now, for this season anyhow, I feel like I can’t do any better (and if I spend another dime on soil my wife will probably leave me). I'm assuming I have all the components necessary to grow anything I have the mind to.

My question is, for a healthy and sustainable soil, did I shoot myself in the foot separating the SFG boxes and contents from the soil below which I can see is just packed with earthworms & microbes and other nutrients that it took me 5 years to get healthy? Will the fabric prevent the soil inside the boxes from regenerating itself? Should I poke some holes in the fabric to allow the worms to come in and do what worms do?

Another question is, SFG says the box only has to be 6” beep (I made one box 12” deep and the rest are all 6”). This garden gets sunlight almost from sun up to sun down, and I know for germination this is great, it’s nice warm soil. But in mid-summer even after being shaded by the plants that 6” of soil has to get hot. Can it get too hot to sustain a healthy balance of microbes? I wanted to make them all 12” deep but it was cost prohibitive.

I get a very high quality pine bark mulch locally, with lots of fines in it, and I'm actually thinking of putting some over the beds to help keep them cool and moist.
I'm an "Urban Gardener". I have no grass at all, only gardens.

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Super Green Thumb
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Joined: Sun Feb 15, 2009 11:04 pm
Location: TN/GA 7b

Re: Earthworms & microbes and nutrients in my SFG.

Well, I can tell you that a number of people have written in here and said that regardless of what the SFG bible says, 6" is not deep enough. But especially since you are saying what is under there is good soil, I think you can fix that by getting rid of the landscape fabric. You are not just concerned about the earthworms. You want your plant roots to be able to grow down in to the soil beneath your six inches.

This is a picture of tomato plant roots, two months after transplanting the tomato:
tomato plant roots.jpg
Those are one foot squares.

The picture comes from here ... 7ch26.html and if you go to Table of Contents at the top, you can find info about the root systems of a whole bunch of different vegetables.

Link courtesy of jal_ut, who has posted it several times. The book is actually from 1927, but the nature of plant roots has not changed.
Twitter account I manage for local Sierra Club: Facebook page I manage for them: Come and find me and lots of great information, inspiration

Posts: 11233
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Earthworms & microbes and nutrients in my SFG.

You have a very nice garden.
Happy gardening in Hawaii. Gardens are where people grow.

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