Damn you Rusty, I thought I had hooked another one, was about to reel him into an experiment and now you spooked him!
Love the "PMS" btw, you need to get that copyrighted!

Hey Bobhead,

Yes it does work, but it is a very difficult to explain why. I'm almost sorry I mentioned it, since it is kinda cutting edge stuff. In thinking about it there may be other ways to achieve tighter nodes, that can be explained easier.

The main reason plants seem to stretch more under HPS, is the lack of blue light in there output spectrum. Simply adding some CFLs or floro tubes to your HPS can cut that stretch down.

Recently, during a UVb experiment I oversaw (there's a thread in Advance Techniques) the main light source was 150w HPS in the grow chambers. Since the UVb we were using was in the form of a 20w CFL, the total watage used was 170w. To keep the non-UVb chambers on equal footing we used a 23w 6500k CFL with the 150 HPS. These chambers went from beginning of veg thru flower. Even tho we grew these plants larger then I normally grow, I was impressed how compact the plants staid. The strech during flower was at or slighly less then 2x plant's vegged hgt, for 5 various strains.

I grow single cola, SOG size (finished hgt less then 18") in all kind's of grows; aero/fog, rockwool and even dirt (well Pro-mix). Here's a pic of a plant in pro-mix in a oversized 6" dia pot, abt 4 weeks into a 8 week flower that was abt 10" tall at pic time that finished around 12". It's a NL cross that oudoors goes abt 6-8' tall, does about 4' normally indoors, but was grown small using floro supplemental lighting.