I'm planting three sisters and am preparing mounds 3' diameter and 1' tall. To begin I cut and flipped grass with a nursery spade then tilled it with a hoe. I then laid container mix on top. I'll use a fork or spade to loosen up soil deeper below container mix and flipped grass.
Is the flipped grass ok, or how is the ground usually prepared? On the one hand I understand the grass decomposing can reduce available Nitrogen because biota are using it up to decompose grass. On the other hand I have used cardboard and mulch on top of bare grass and have had great success planting that way.
Come to think of it, for my next mound I'll try cardboard. As the base below a pile of container mix and mulch.