Like Bob I have had disastrous results with sun drying bulbs. I decided to do this last year after reading how great is was on daffnet. Until now I haven’t broadcast this experience to everyone but I probably lost over 1000 bulbs last year using this method. My advice would be to stick with what works or only try this method on a few bulbs so you know it will work for you. I had one bed I dug and literally lost every single bulb. The only cultivar that yielded positive results was n. canaliculatus. It bloomed for the first time ever.
Kathy, from northern VA.