I have been waiting for 2 years for a good crop of Japanese Maple seeds (keys). Last year they didn't form because of the bad weather we had here in KY. This year I have collected plenty, after they fell off of the tree. I have them planted in trays all over the place. Is there anything I need to watch for so I'll get a good group of seedlings? I do not want to ruin this years crop and have to start over again.