|This past summer, I grew dahlias (the large variety) and had pretty good success with them. However, as the summer got later, the stems (at the top) seemed to get thinner and wouldn't support the new blooms so they just flopped over. I staked the plants at the bottom and supported them pretty good but the growth at the top of the plant seemed weak. Did I do something wrong or do I need to prune them a certain way? Second question, do I need to divide the dahlia clumps after I pull them out of the ground or can I just leave them all together, not divide and replant them the way they are. I'm somewhat nervous about trying to divide them.