Same here, Eddie. I still plant sets in the fall and plants in late winter. The sets will always bolt early because they are in their second stage of growth, the reproductive stage, and want to make seed. Unless you grow your own sets the ones you buy from garden centers/farm stores are usually imported, often from Holland. I grow them because they make the best green onions and, more importantly, frying onions (cooked as you would cook greens.) Yummy!
I also find there is a much bigger variety to choose from when you grow plants, either from seed or from another source. And yes, I highly recommend Dixondale Farm in Texas for fantastic plants and cultivars. Glad you referenced them, dave!
Rob, if you're growing from sets you wont get large onions. If you're growing from plants it may be you need to bump up the phosphorus as it makes for a larger happier onion. And of course, ample sun and water.
Happy onion growing!
Shoe (who just received his onion plants in the mail today.)