Producing "Stocky" Plants?

[Greatgardens]

I've never really been able to do this indoors. Outside is quite easy. And of course, determinate plants seem to produce stockier results than indeterminates. (Dwarfs and Micros are no problem at all.)

I've certainly read that if you use really big lighting arrays (now with LED's), that it can be done.

But how about with just fluorescent tubes? My starting setup now has 4 T8's so I'm in the range of 11,000 - 12,000 lumens with 6500K bulbs.

I've read that 14 to 16 hrs per day is a good length, and of course have the plants close, but not to the point of burning the leaves. And lower temps supposedly help -- 60 deg. range. I can do that in my garage.

Anything else important? Anything I've got wrong? Anyone use some type of growth retardant?

-GG