It's not that i don't understand fertilisers more that everyone i have spoken to has told me to use a different one and so i don't trust them cos so many problems stem from over use of fertilisers or misuse of fertilisers. I'll wait for a better understanding before i go into hydro. Do my research. What do u mean about don't let them stretch anymore ? do u mean in height ? and how do i stop them from stretching ?