HPS lighting question; height from plant tops

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drpsholder

Active Member
I will be growing 2-3 plants in my closet which measures 4x2x5, with 5 being the height. Shelves start at 5ft, and I really don't want to remove them, but can if need be. Ceilings are 8ft, I think.

So, can I secure HPS light to the underside of bottom shelf and not run the risk of plant burn? How far above the plants should a HPS light be?

I just don't want to burn me ladies!

Thanks and any advice is much appreciated.
 
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erbium

Well-Known Member
About 18" . It is better to have the light on a chain or something so you can control the height . You could go less if smaller light and good air flow .
 
cheetah2007

cheetah2007

Well-Known Member
what wattage man?!? if u have good vent u can get a 400W 6-8" from the plants.... otherwise they will strech!!
 
floydfanx6

floydfanx6

Well-Known Member
i have a few 150 watt hps's i can get them 5-6 inches away since i have good air flow on top of the plants. For every inch you can get your lights closer(without burning them) you will have an extra inch of cola budd,,,that simple,,so try to get a lot of fans blowing on your tops,so you can move it as close as possible..When hooked up just put your hand over the tops,if its comfortable enough to leave it there the whole day then thats a good level. Obviously more fans,lets u lower your hand more good luck
cheers
 
oh really???

oh really???

Well-Known Member
you could do a vertical setup and put the plants on the shelf tilt them out and then put the light in front of the shelves.

. . . . .is your light in a hood? or free floating?
 
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drpsholder

Active Member
Hi and thanks for all the input.

I was planning on a 400W HPS, but think I can get away with (2)150W or (1)250W for such a small grow of 2-3 plants. I also plan on doing LST to conserve space and maximize yield.:joint: (of course, i will start a grow log, so add me to your friends list and stay tuned. Germinating seeds today!)

If i read correctly at HTGsupply.com, their 150W HPS system is only a HPS and not convertible to MH. The 250W HPS system seems to offer both HPS and MH bulbs. I have no idea if i need to purchased a switchable system or can I just buy a conversion MH bulb to fit HPS non-switchable system. HTGsupply customer service will help me with this problem, but of course your opinions count too.

Eventually, with more experience, I would like to convert upper part of closet to cloning/vegging, then leave the bottom for flowering, but this is my first grow...............so keep it simple stupid. (Stupid comment refers to me, not you!)

Also, there seems to be a difference in opinion in height distance from top of plants. No matter, all answers suggest that I can place the light in my closet without fear of burning........with proper vent. and circ. Thanks again.
 
Dabu

Dabu

Well-Known Member
floydfanx6 said:
i have a few 150 watt hps's i can get them 5-6 inches away since i have good air flow on top of the plants. For every inch you can get your lights closer(without burning them) you will have an extra inch of cola budd,,,that simple,,so try to get a lot of fans blowing on your tops,so you can move it as close as possible..When hooked up just put your hand over the tops,if its comfortable enough to leave it there the whole day then thats a good level. Obviously more fans,lets u lower your hand more good luck
cheers
Click to expand...
Good advice right there. ^

I was about to type roughly the same response, lol.
 
floydfanx6

floydfanx6

Well-Known Member
theres no problem with an hps in the closet everyone does it,,,the problem is with your temps,,i suggest a normal big fan osilating in the corner of the closet,,try to get a good pc fan to blow on the tops of the plants,,,and very very imp for closet grow,,get a pc fan i mean a good one 88mm,and put it on the hps,,on top of it,heat rises to the top so this fan will blow the hot air out of your closet,it helps a lot,,i have 2 150 watt hps's and about 20 cfls in my mix,,and my temps rarely go above 78
cheers
 
floydfanx6

floydfanx6

Well-Known Member
be careful with how u mount your hps,,,an hps WILL cause a fire if it falls somehow its very not like cfls,,mount it very well
 
smoove

smoove

Well-Known Member
With 8 square feet of potential canopy space (4' X 2'), you may regret getting anything less than a 400w HPS. To maximize your space though, you'll need proper ventilation and incorporate some form of training technique (LST, SCROG, etc..)

I grow with a 400w HPS in a cab very similar in size to the one you plan on using. 1 simple solution to hanging your light is to install hook screws directly into the shelf and hang your light from a chain which can be raised and lowered as needed. There are also flixi-hangers which I hear work great.

As for how close you can keep the light to the tops of your plants, there are several factors to consider, but a general acceptable distance for a 400w HPS is about 12" (give or take a couple inches depending on the brand.) If you're using an air cooled reflector you can get a bit closer to your plants than you would be able to without (as close as 6"-8" from the tops) I'd recommend looking into it if you haven't already as this is one of the most efficient and cost effective methods of keeping your cab temperatures under control. As several posters have mentioned, ventilation and temperature are very important with such a small grow space. The cooler you can keep your grow room the closer you can get the light to the tops.

Hope this info helps. I mentioned I grow with a 400w HPS in a very similar sized cab to the one you have... if you're interested you can check out my last grow from the link in my sig.

Good Luck.


:leaf:
 
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stikup1979

Member
I have 2 400w hps on 5 plants,and I blow 2 fans on angle upwards so it blows inside hood to cool heat from lights.I have mine about 6 inches from bulb,and my buds have doubled in comparison to previous first grow with light 12 inches away.so if u want long fat buds keep your light as close as you can get it.good luck
 
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