The next step after building my raised veggie garden structure was filling it. As Lars pointed out on that initial post, the official Square Foot Gardening method calls for filling such a bed with the following:
- 1/3 peat moss,
- 1/3 compost, and
- 1/3 vermiculite.
The compost is supposed to come from 5 different places, e.g. cotton burr compost, worm compost, tree compost, etc. I am sure this mix produces greatness, but I went a slightly different direction. I had a huge pile in the side yard of Living Earth Technology’s “clay buster” left over from the landscaping project out front. It’s a 50-50 mix of expanded shale and compost (who knows what type). Living Earth has a few locations around Texas and I highly recommend visiting them if you can. Here’s their description of expanded shale:
Expanded Shale is a by-product of highway building material processing. It is a gravelly clay particle that is kiln heated to about 1,600 degrees Fahrenheit. The result is material, which is very hard, yet porous and angular. As a soil amendment Expanded Shale aerates the soil yet absorbs water, releasing it gradually. This material positively breaks up heavy clay soils. In landscape applications it improves soil properties and allows plants more air and water.
Green, right? 🙂
Anyways, this is what I used to fill the bed, plus some finished compost we’d cooked up ourselves, and a big cube of peat moss from Home Depot. This was my first experience using peat, and I must say the wine people are right — red wine does smell like peat!!! I can now say that at wine club without being a poseur.
By using this mix I am making the assumption that since the clay buster sat out for a few months, the compost has broken down enough not to burn the plant roots. I also assume that the shale will act sort of like the vermiculite. The shale has the added advantage of not breaking down over time like I hear vermiculite does.
I cannot say with certainty that this mix is the ultimate for raised bedding. We will just have to find out as the growing season progresses.
Some shots of the planted garden: