MH does keep vegging plants shorter and tighter, and whoever mentioned raising the lights is correct that it'll probably aide stretching a bit if clones are what you're shooting for.

As for using HPS for veg, while I won't say that it's any 'better' than a MH or blue-spectrum fluoros, I did use nothing but HPS for quite a while before I ever discovered conversion bulbs and switchable ballasts. I never could allow the plants to grow vertically, or they would have damn near reached the ceiling, but I did get to do a lot of experimenting with LST methods due to the extra stretching, as well as topping/FIM techniques which I believe may have improved the eventual yield.

So, all in all, HPS in veg might not be ideal (depending on what you're looking to achieve), but it works in a pinch, and in this instance, would almost certainly have assisted in cloning at such an early stage.

Just my :twocents:, for what it's worth.
Mr. Clandestine Reviewed by Mr. Clandestine on . This makes no sense ........... I have had 5 plants under a 400w MH bulb for almost 2 weeks now and they are green as hell and have nice big, fat leaves but they dont seem to be getting taller. A few grows ago when all I had was an HPS bulb I didnt seem to notice this type of behavior so I guess my question would be does an MH bulb slow down vertical growth??? At the rate they are going I'll be retired before I can clone them lol (but really crying :( ) Rating: 5