Put some wood in the bottom
Discussion
Yes, thanks. I was wondering how to fill them a bit without putting a ridiculous amount of soil in them.
Do a quick read on Hugelkulture
Wood decays, stores water.
I would consider filling them at least halfway with wood and create a woody hugle bed kind of thing with at least a foot deep of compost/good soil to plant in on top.
That sounds great. I have a lot of brush around as well.