I use that bag method to collect pollen too^. the longest so far for me is a year. I vacseal the pollen at room temp with a desiccant bag inside and into the freezer. I find if I retrieve some that I cant expect to refreeze with any success, but a year later, although diminished success, some is viable. only funs for me, but seems like a year and a week and its dead-so far with my haphazard methods.