What do you knowledgeable people think about using the old grass and attached clay/dirt I dug out of one area of my yard (to lay concrete patio) to build a raised garden along the back wall of my yard? I would keep it up with a retaining wall and place a couple inches of top soil on top. I don't know if trees and flowers could grow in it or if it would just have the grass grow back out the top. Could tree roots grow though all that dead matted grass underneath? Thanks for any info.
To aid aeration, and decay, till the sod if you are able, and also add compost. Clay will harden when dried out, and cause water retention issues/poor drainage.
Another thought: how high will the retaining wall be? I ask because it's not a good idea to bury sod, or any stuff that you want/expect to decompose, too deep. The conditions are suitable only in the top few inches of soil (moisture/aeration/humus/microherd populations) and they become less suitable the deeper you go. I agree with both previous suggestions: kill it and chop it before your incorporate it. Good luck!
