I'm looking for input on the planting medium to use in a crevice-y tufa garden. In my readings, I've found very different recommendations on soil mixes to use.
I'm starting with a berm, and the tufa form a ridge in the middle. I'm going to try to place the tufa pieces tight together, though given their irregular shape, the crevices between them will be fairly wide. My climate is relatively warm and humid (mid-Atlantic).
Should I stick to a sand/gravel mix to keep things lean? Or will sand and gravel be too unstable, washing out from between the rocks? And finally, should I use the same mix in the berm as in the crevices?
I'm looking forward to hearing from those who have constructed similar gardens.