Are they getting enough sun? As long as they get enough sun, and the right amount of moisture and are growing healthy, there shouldnt be a problem.

I was at a customers home about 3 weeks ago, and she had bought 2 little dahliettas with flower buds just about ready to open. I came back 2 days ago, and they hadnt opened yet, and were about the same size as before(the buds), but the problem was, they had almost all their leaves eaten off by slugs, since she wasnt watching them or applying slug bait.