It varies, ive had strains that were ready in 50 days, other tropical sativa strains can take 12 weeks. if you dont know what you are growing than you have to just go by the eye test.
8-12 weeks on average.. some more... some less... strain dependant... lighting also plays into it... if your lighting isnt sufficient it can extend the flowering period... different pruning techniques can slow flowering.. but if you want a guide line 8-12 weeks... indicas ripen faster than sativas...
ok ok thx guys right now its all bag seed (my first grow) i have 8 fems under a 400w hps im about to pump up the juice to a 1000w
its all in a grow hut (bomb)my next grow will be some dank seed
im just experimenting wits some three stage powerfull flowering nutes