a local hydro guy told me a great way to increase my yields....
start your plants regularly- 24h light or 20,no or small amounts of grow nuts building to full strength.
once your plants are about 2 ft tall switch to 12h light 12h dark, but keep feeding with you grow nuts. this will stop your plants from streching to tall, they will still grow up but not as rapid, he says this will make a healther plant with more flowering space. they will pre-flower but wont bud.
leave them like this untill desired hight, plants at this point will be very full and healthy, now... switch to your bloom nutes and watch your plants explode!!!!!
has anyone tryed this method??? sounds right in principal
Consider for a moment that if this guy knew what he says he does, would he be tending the counter at a hydro shop? I think he'd be running a grow op if he was really switched on... You'll find as just many qualified electronics engineers working the counter at your local Tandy/Radio Shack.
Grow nutes during flowering will give you pretty much the opposite of what was suggested to you. Flowering plants running on veg nutes will tend to elongate and buds will be more leafy than when on a high-P nutrient.
It takes about 4 weeks for a plant which has been in veg to switch fully to flowering habit. During that time, the expression of veg habit will progressively taper off while bud formation progresses. They absolutely don't need any encouragement toward being any taller.
It is mostly the 12/12 photoperiod which causes plants to flower, but high-P nutes and to a lesser degree, the red-yellow spectrum of HPS lighting also trigger flowering. High P flowering nutes both encourage flower formation and limit elongation/gaining of overall height.
In my SoG op, clones which have been under 24/0 veg light, once they have a good spray of roots, get chucked right in to 12/12. As said, they take about 4 weeks to stop displaying any veg habit and start packing on bud mass in earnest. In weeks 1-4, they triple to quadruple in height but slowly stop growing vertically by the end of wk 4.
If you vegged up a plant to 2ft then switched to 12/12 while on veg nutes, you'd end up with a very tall plant by the end of wk8. Tall plants are not the indoor grower's friend.
Even the mighty 1000HPS can only penetrate foliage so deeply- even with lower branches and excess lower foliage removed, decent buds will be produced only about 35-40" down the mainstem. Below that, buds tend to be fluffy and small. In SoG, we deliberately grow short plants and just don't grow the poorly productive lower parts of the plant.
Ask your shop clerk if s/he thinks tall plants are a good thing for indoor growers- and you'll get a good idea of what page that person is on.