When to start flowering?

Hi all

I read somewhere that I should start flowering my plants (ie change the light cycle to 12/12 once the plants get about 30cms in height.......

That seems quite small to me....

Any rough ideas greatly appreciated....it's northern lights, n I have 2 plants each looking nice n healthy and about a foot to a foot asnd a half high....

Not sure how long they were in veg b4 I was donated them..

Pls excuse my obvious ignorance!

Thanx all......this is a great site, everyone is really friendly n helpful

i find the way to deside on when to flower is to deside what you want to end up with and work back from there comming up with the best way to get it.

i find with northen lights that they finish at about twice the hight that they were when they was put into flower or less given good conditions. i have flowerd nl that streached as little as 9" on a 2' plant but that was under some preaty heavy lighting.

so if your plants are 18" now and you put them into flower you can expect plants around 2.5 to just over 3foot (3 being most common) depending on light and other factors.

if you want 4' plants then flower at 2' tall etc.

how tall do you want your finished plants?

hi

cheers for that

i reckon i want them about 4 foot max. so i'll give em another wee while then switch to 12/12

Thanks again dude