It breaks down in about 2 weeks or so I'm told, so some say only the first 4 weeks of flowering every 3rd day. Should have trouble free plants. I started flowering 6 days ago , My plants havent sexed yet, but I have sprayed them once and am due for another tomorrow. No Ill effects either. I will stop in week 4 unless trouble arrives after. I foilar feed every other day, with plain Ph'd water, I have had no signs of any pests to date.