BrownAcid

How far should the lights be above the plants. Plz help me out.

Xzoomd

on what youre using. Flo.s, an inch or two. 70w hps, prolly 6-8 inches.A 400w hps, about 12" with ventilation.

X~d

Phread O'Hinton

The heat's the issue here. With flouro's, they run pretty cool, so with good air circulation you can even have the leaves contact the tubes.

HID lights, MH in particular, run much hotter. The rule of thumb here is that if it's too hot to be comfortable for your hand (at plant top height), it's too hot for the plants.

Ideally, you should adjust the light daily, keeping it as close as you can throughout the grow. Realistically, you raise it so that the growth won't get too close...

ssj4vegita

I've been keeping my HPS about 1 1/2 to 2 feet from plants...should I move it closer?? My nodes are less than inch apart, and I have ducted A/C underneath the light to keep temp down. Advice please...I'm a newbie at this.

Xzoomd

I use a 400hps w/o any elaborate ventilation & I keep it around 12-14 inches, sometimes it might get to within 10 (but thats pushing it alittle close)
Yeah the hand test is a good indicator. Leave your hand there for about 60 seconds, if your hand doesnt become uncomfortable it should be ok.

X~d
ps Welcome to HC.com

ssj4vegita

Thanks...I'd been wondering about that, cause I got enough lumens to put it as high up as I want......but I wanted to get the max out of it. thx alot!

ssj4vegita

haha - (golf clap)

BrownAcid

hmm k. lol

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smokinrav

A lot of how high to place the lamp has to do with how many plants your growing and the space they take up. To effectivly light the sedges of a garden, the light has to be higher above the canopy.

just my .02

Smokin