I planted 31 wax begonias from a 50ct tray about a month ago. I had planted marigolds from seed in this spot last year but didn't think they were getting enough sun so I thought begonias might work. They are still alive, but have gotten smaller, not bigger. After about 3 weeks when I felt they were needing something I went back and pulled them up adding some better soil and compost and replanted. It was obvious the roots hadn't grown at all. We did get a ton of rain in May right after planting and our spring has been cooler than average. They haven't improved much if any since replanting. I have removed several leaves that have looked brittle and brown which is why they are smaller than when I planted. I have only seen a little new growth on a few plants. Any ideas what the problem could be or what I could do to help them grow?