Last year I collected seeds of Ipomoea pandurata only to discover later they were host to some beetle eggs, which pretty much wiped out all the seeds during winter storage. This year I went back to the site to try to dig some tubers, only to find that the site is littered with builders rubble, and the tubers are down below inbetween all the buried rocks and blocks and bricks and such. So I was forced to be content with harvesting more seeds. I'm trying a new tactic. I sowed 1/3 of them directly into my garden. I placed 1/3 of them in the refrigerator, and the other 1/3 in the freezer. I can let you know again in spring time if I had any luck. Meanwhile, the 1 plant that occurs naturally on my property has not set seed in several years. Hmph! Dennis in Cincinnati, Ohio, USA (where winter is HERE)