Are they outdoors Coraliefitz? If so, it's too early as the nights are still cool and there is still a chance of frost. I have all my bedding plants out during the day but bring them inside at night. If they are inside maybe another member could help with your question as I am not sure what the cause could be.

are they over watered, they go limp as if they are too dry if waterlogged. Yellowing leaves could be a syptom of that. but if outside already then they are too cold.