Dry it a few days in an inside dry location where there is at least a little air circulation and away from sunlight. Then I store in small glass test tubes with a piece of cotton ball plug at the top. And then store samples in a non defrost deep freezer at around 0' F. Any deep food freezer would do just fine but you then should then put sample containers like test tubes in another freezer bag sealed to avoid contamination with food stuffs. I have keep pollen for 4 years and it was still good. I'm supposed to rotate my pollen yearly and throw out anything more than 5 years old and replenish with new. But, I'm a lousy housekeeper and my pollen freezer was in more disarray than Aunt Nellie's spice cupboard. So, a week before the convention, I went to put pollen in there, It had a breakdown, everything had thawed and all my pollen was molded. So that did it for me---it took care of everything. And that freezer was pretty new--only 3 years old.
