I think it has been two years now since I was plagued with the aids of cannabis-Powdery Mildew. My mentor and garden center/owner recommended I use this product vs bleach. I used a pump style sprayer for plants (2 gal tank). And sprayed my walls down with it. You don't have to rinse it. It helps prevent it from ximf back which bleach does not do. It's not that expensive and your plants are worth every penny. Garbage in! garbage out! Spending a few extra pennies for prevention is always well worth it.