I'm not an expert on this but I would think the gourd would have to dry naturally for the seeds to be good.I also see no reason why they wouldn't survive harsh winters.They have survived in nature for hundreds of years.They would be protected inside the gourd.If you are worried about that maybe you could put a few gourds inside a garage or someplace protected to dry.I cut the legs off old pantyhose,slipped the green,mature gourds inside and hung them from the rafters under my deck.They dried beautifully!..........Lillie

Last year was my first to save seeds, I cut open many gourds and put the seeds on cookie sheets on the floor under a ceiling fan, they dried good that way and grew this year also. I did learn to sort the seeds, ones that were white were uselly hollow inside. Good luck.

Sandy