as long as you don't put too much yeah, plants love that shit man, in the end it turns into water, after popping an extra o2 molecule in your res, plants love o2 and water. I use it quite a lot, the best thing to do is go get some 29-32 percent and dilute it down to a strength of like 3 percent, personally I don't even measure, I just dilute some in another container and pour it in the res. Now I'm running bennies in veg so I'll not use h2o2 unless I have a problem, before I started using the bennies I used h2o2 a lot. oh and p.s..... if you get the 29-32 percent be careful, that shit will take your skin off until its diluted. You can also just use 3 percent from like walgreens but sometimes they put other shit in that, the 29 percent has no additives.