from what I have read pollen only lasts about a month or so. Could be longer could be less depending on environment. A good scrub down and a little wait should do the trick but a good scrub will be fine. By the time its flower time you should have no worries even if you didn't scrub anything unless you do a 3in grow. Ya know the 3 weeks veg and the flower thing. I just got this from what I have read. Still learning myself.