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 16â€™ x 19â€™ 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 canâ€™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 6â€ beep (I made one box 12â€ deep and the rest are all 6â€). This garden gets sunlight almost from sun up to sun down, and I know for germination this is great, itâ€™s nice warm soil. But in mid-summer even after being shaded by the plants that 6â€ of soil has to get hot. Can it get too hot to sustain a healthy balance of microbes? I wanted to make them all 12â€ 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.