 You can use straw. Same goes there, that it hadn't been sprayed with a herbicide to kill the weeds and the wheat. And you can even use a newspaper. You can just lay a newspaper out, cover the soil. It doesn't have to be the full three inches thick, of course, if you use a newspaper. But, again, that will shade the soil and hold the moisture in, and that will work really well. I was trying to keep the roots cool.