About 3-4" deep. I think any size gravel under 1/2" would hold form. I prefer 3/8".
The purpose of raking is to meditate. Nothing last. Let wind and rain, or raccoon runs through it.
Now that it's been nearly 18 months, how is the moss holding up?
Author of Midlana, Build this High Performance Mid-engine Sports Car. http://midlana.com/stuff/book
Any updated pictures with the succulents?
Susie