I agree their is no use to use mulch in your grow room, you are already using prepared soil so, there really is no reason for it, but for your lawn or your flower bed, yeah absolutely. also in our environment pests, diseases and viruses are easy to keep out, usually; so there should be no worrying about this stuff, I have seen grows out door here go for a long time naturally and they still don't have pests or even root problems. it is a sight to see though lol magic bush, I have seen some deer love that area though haha