[huntoften]

Robin...love that rock work! Eventually I'd like to do the same with the native limestone on my property...eventually.

As for filling them. I till the existing soil...it was grass at one point in the past. Then I cover with a layer of compost...I buy it by the yard from recycled yard waste...leaves, sticks, grass etc. Then I till it again to avoid a stratification layer. Then I fill the rest with a 8-1-1 ratio of compost/perlite/vermiculite.