cool, dark and dry is all that's needed for long term storage. i've kept mine in pill bottles inside containers in the back of the fridge for several years and still have good success with them and same for in desk drawers. freezing can burst the cells if not properly dried 1st and although many do store this way, it is generally advised against keeping them in the freezer. the c99's in the current grow pics are from seeds over 5 years old for instance and had 7 out of 8 germinate with 5 f's this round (these have been stored in the pill bottles in the fridge).