I wish I knew. I've come to expect my spring crops to be a lot more hit-or-miss than my summer or fall ones. I agree that the weather seems to suddenly and rapidly heat up, causing lots of spring crops to bolt or otherwise become useless. Some springs I get nice broccoli and peas, etc., others I get close to nothing. I'm not expecting much this year, unless the cool trend holds into June. But we will see, this will be another experience under my belt when the season has gone by. I've only been growing in this exact location a few years. Sorry I don't know anything about onions for scallions either. I only grow mine for storage.