I stumbed onto the "baked rice dessicant" tip while looking up how to regenerate silica gel by baking it at 250 F for several hours (but no hotter).
I tried to find out the best temp for over-drying rice, but all they said was "until it's not-quite-brown".
Someone sent me some fresh seeds they hadn't quite finished drying yet - in a Ziplok along with dry rice grains in the Ziploc! The seeds were much smaller than rice grains, hence easy to separate.
I used to worry about OVER-drying seeds, but the humidty cards suggest that isn't a problem when I use only a small pkt of silica gel (1-2 tablespoons). Usually I open and close the jar a few times while setitng it up, and the seeds themselves are in Ziplocs that slow down the rate at which they lose humidity, even if the air in the jar itself is "too dry".
Plus, I have paper labels inside each Ziploc, and paper absorbs humidity and then releases it gradually. So I figure that acts as a "buffer" for the seeds.
Whenever I check a pkt, the paper is not "cracking-dry", so I figure the seeds are OK. And they do sprout for me, so I haven't killed them with too much dryness.
What I read suggests that seeds last longest when the humidity and temperature are both low and STEADY. Fluctuations, not so good. For a while I was packing 2x3" Ziplocks inside bigger Ziplocs, so there two barriers to moisture movement. But now I think that is overkill. Glassine envelopes take up less room, when I wnat to group together 10-20 Ziplocs by variety or genus.
