I also add large rocks (being a rock/mineral collector has given me a nice pile of "Leaverite" (should have left em there) to pull from). Addition of large rocks (once the stems have broken through) adds 'ballast' to the creation as a whole, but more importantly adds the weight necessary to help stabilize the creation when beset with summer thunderstorms. The glories get thick enough growing up those trellis' that were they not grounded securely they could sail across these midwestern prairies like a land ship. Sometimes I also surround the large pots with large bricks to provide even more support structure.
