Hi Molly! I read to fertilize winter blooming annuals with blood meal because it supplies long lasting nitrogen through the winter and that is what I used to do. More recently I've used a pelleted slow release fertilizer. However, I've read where some pelleted slow release fertilizers work with the amount of water they receive and that others work according to warmth. The warmer it is the more fertilizer they release. I don't know how to tell which one I'm using. water releasing or heat, but it does seem to work.