I love Dahlias and this is the first year I have planted them. I purchased them from a local nursery and I am finding that the flowers don't always fully open. They sometimes appear stunted, and sometimes the stalks do not grow as high, but start to flower when they are at the shorter end of the sten. Please help. I have these planted alone - no other plants sharing the pot, and they are such a pretty flower, I do not want to lose them. Are they typically a "fussy, high-maintenance" flower.