Hi Mike,

great questions.. and there are no absolutes..
but here it goes..

Most cannabis plants will double, tripple and sometimes even increase in size by 5X's there vegetative size once flowering is induced (12/12 lighting). The younger a plant is forced into flowering, usually the more it will grow when flowered (proportional speaking of course).

A plant that is flowered at 4 inches tall may get 24 inches tall upon flowering(6 times taller).

Where as a plant that is 10 feet tall may only get 15 feet tall (.5 times taller) upon flowering.

So why flower at 20 inches.. strickly speaking of indoor gardens....
HID lights are nearly usless at more than 24 inches (unless you just want to shp at costco underneath them)... Every 12 inches these lights loose half of their GROWING power (lumens)... SO if you FLOWER a plant at 20 inches.. and it grows another 20 inches.. you now have a 40 inch tall plant... to adequately light a 40 inch tall plant you need lots of side lighting.

THAT being said.. many many people grow 10- 60 inch tall plants under 2 - 1000 watt HPS bulbs and harvest 3-5 ounces per plant... once every 3-5 months... it can be done.. it is just not the most effcient method of growing in my opinion...

I also come from a background of growing plants very very close together.. making it IMPOSSIBLE for any light.. even the SUN to penetrate more than 6 inches from the highest point in the canopy.

iloveyou

WHEW!!!!!!


BUT wait, there is MORE.. LOL

MAD is growing with FLUORESCENTS.. he should have flowered when the plants were 10 inches tall... Fluorescent have VERY VERY minimal penetration and must be kept DIRECTLY in the area of desired growth..

iloveyou