nutes have an "NPK" rating, for flowering you want something that is high in "K", low in "N", and med/high in "P". Thats a general rule of thumb. Since I havent flowered yet I cant tell you from experience but I am using an organic, seaweed based product myself as well as superthrive. On top of this, I am going to start using a tea from my local hydro store that is full of beneficial living organisms. I cant wait to get some!