I started with Ortho spray (did nothing), then a spray of a tablespoon of Dawn in a gallon of water (decent but not wholly effective, next day had live ones again) and finally what killed them was Dr. Bonnar Peppermint soap combined with No Pest strips. This was all in veg. I didn't wait to try the Dr. B's before hanging a strip, did them together, one treatment with the soap followed by one strip hung in the veg box for a week and they all went to spider mite heaven. The strips are toxic if you breathe it too much so be careful, have read different opinions on whether you can use them safely, up to you really, but for me they were the bees knees. I hang it occasionally for 3 or 4 days at a time just as a preventative measure, then into a zip loc bag it goes. Mites really suck, made my plants all spotty and actually killed one big clone. I felt lucky to only lose 1 plant to them, after reading horror stories and watching YouTube videos.