I need to use plants over a gravel area that is necessary for draining water away from a building foundation. A landscape fabric will be used on top of the gravel. Where the gravel is too deep to use, direct contact with the soil, how deep should the soil be to support average sized perennials?
Xeriscaping Over Gravel
Certified GKH Gardening Expert
If you can get at least 18 inches of soil, that will minimally serve your average sized ornamental plant. This does not cover trees and shrubs, but most things smaller than them. If you can go deeper, that would be better even though.