stunting WW growth ?

is there any additives you can buy in the uk that will slow down the growth of white widow because i have a ecobox vertical growing system and my white widow are going crazy they have been averaging 2inch a week and thats too quick ????

please i need answers

ok what about PBZ does anyone know where i can buy this and does it work ?????

Why don't you just top it?

they are topped but still going crazy
i just want to stunt/slow the growth
there must be a way

Ive read that this works pretty good:

http://www.horticulturesource.com/emerald-triangle-bushmaster-qt-12-case--p232/

Only problem is, that I think its supposed to be used before you enter flowering to reduce the stretching phase, so I dont know if it'll still be of use to you.