If your flowers look dead, with grey or brown patches, then you may have bud rot. To be sure, you can check out our guide on bud rot, or get a picture of the problem to us in our cannabis growers forum. Keeping your grow room humidity below 55% during flower, and using plenty of fans will help to avoid this problem. But most gardeners will experience it at some point. Be extra vigilant in the last few weeks of flowering, and keep temperatures and humidity at ideal levels.