Hello. Looked in my book The Cannabis Breeder's Bible by Greg Green. He says to collect the pollen after it has fallen from the flower, on the leaf or put a piece of smooth paper out to collect it. Put the pollen in a black film canister (the old 35 mm film ones) and it can be frozen for up to 18 months. He says the pollen will not be viable after that. Best to use with in 3 months. Good Luck. Chuck.