A friend who has a veggie garden and does not grow pot will be happy to add your used dirt to his beds in spring. I keep a lawn-size garbage pail in the cellar to accumulate used dirt all winter since it snows here too, and then give it to my buddy across town for his container-grown tomatoes. It takes a nice flush to get the worst of the fert salts out but he has perfectly respectable yields of fruit using it.