>> Sometimes I will put the seeds/heads in regular letter (paper) envelopes to make sure they dry out real good.
Me too. Either paper, or plastic with something propping the mouth open. That's one reason I like seed labels on little slips of paper I can move from tray to envelope to Ziploc. If the label is always with the seeds, they don't get confused as often.
I wonder how much power those little desiccant pellets have, after sitting in a plastic bag for months. The desiccant only helps if not yet exhausted, and being exposed to open air with any humidity exhausts them pretty quickly.
They need to be sealed into a small space to do a good job, and since everything leaks somewhat, they still need to be replaced yearly or more often.
I figure that mine get used up because I open and re-close each seed jar too often. As soon as I open the lid, the jar is filled with (humid) room air. Now, sealing it back up, the desiccant has to absorb and hold all the water I let in.
That's why I bought a pound of flower-drying silica gel and store it in tight jars. When it has all been used once, I'll spread it on a shallow pan and bake it at 225 - 250 degrees F in the oven for a few hours, then seal it tightly. Tyvek bags melt at 250 F. Silica gel may be damaged above 250 F.
One pound makes many coin envelopes with 1-2 tablespoons each. This has lasted me 3 years for 10 seed jars, without ever regenerating any.
Now I use humidity-indicating cards and I think 25% RH is a better humidity level than 10%.
I use less silica gel in each jar, and I make sure to open them at least every few months. Since the seeds are inside Ziplocs inside the jars, the seeds have less humidity variation than the air in the jar does.
But if some newsprint stored with your seed crinkles, it is probably dry enough!
