Hello. This is a tough question. As you can see by the answers, people attack one another over this answer. I would rather people help one another than just be trolls. Some say this and some say that. I flush and I am not going to quite just because some nutrient co. put out a study that says you don't need to. I think it helps. I was at a cannabis conference earlier this week and asked Remo Colasanti owner of Remo Nutrients about flushing, he said "yes, defiantly it even says that in our grow charts". So it depends on which nutrient co. you ask about flushing you get a different answer. How about that, I said my piece without calling anybody names. Chuck.