yes but I would place landscape fabric on the surface so that the rocks don't sink down and mix with the potting soil. Actually any kind of fabric that will allow water to filter into the pot will work, burlap will work also. NEVER plastic! This is just an aesthetics issue. If you don't mind rocks eventually mixing with soil, then you don't need to bother. I do it because I don't want to be replacing rocks every other season. The fabric keeps the rocks from sinking/disappearing into soil.