that all depends on where you live as to your first frost. I don't expect one in my area till mid november. Others have already had a first frost this year. the signs to watch for would be typical weather changes for your area such as cooler temps,fall leaves, migratory animals leaving or that have left or you could consult the farmer almanac and see when they expect a first frost for your area. They will get it at least close so you can plan for it.