how close can you keep your light with your plants?

[Guest]

it's a 4 week white widow in a 2 gallon container in veg. for another week, anybody have a chart or anything? this lamp has a glass that protects the plants from touching the bulb directly, it's a 250W MH for veg, HPS for flower

 

[shrike]

dnb

It depends on the wattage of the light and if you have a power vented light hood or not.

That said, if it feels hot with the back of your hand its too hot for a plant.

Cheers

 

[Guest]

dnb

It depends on the wattage of the light and if you have a power vented light hood or not.

That said, if it feels hot with the back of your hand its too hot for a plant.

Cheers

I'm not sure what you mean when you say power vented, you mean if I have a fan directly connected to the hood? if so, then yeah there is a 4" vortex directly connected. the hood itself doesn't really get hot at all, the fan work pretty good.

 

[Sport Farmer]

Well depends on your setup, like the person mentioned above. I keep mine 5 inches from the plants. BUT i have a glass cover on my hood and a legit exhaust that fully exhausts OUT of the closet. I use a 400w HPS.





If you don't have a glass hood i wouldn't even think of putting them closer then a foot or 2 with a HID light. But it sounds like you have the tempered glass shield. I can hold my hand on the glass and its warm to the touch but not hot enough to make you move your hand.

To be safe id say you might want to leave about 10 inches of space between your tops and the lamp.

 

[dre86]

exactly, I was recommended to keep my 400 watt HPS 50 cm / 1.5 feet from the tops of the plants but notice the temperature right under the lamp is about 28°C and would still be okay for my plants. I have a big desk running right under my lamp though. You can measure the temperature by holding your hand under the lamp, if it's too hot for your hand it will most likely be too hot for your plants too. A thermometer comes in handy too

 

[Blackmelo]

Off topic but I just realized something!!! I always measure distance to light bulb and have always wondered why I keep mine so much further away than evry1 else but now I see Sprtfarmer saying he keeps his at 5 inches and in fact his bulb is further away than mine at 10 inches.
Lol. Distance to bottom of hood is not the same as distance to bulb...

 

[mpro]

Right now they are 3-5 inches away, depending on which plant.



I don't see temps above 82 in the room. RH below 65% 400hps cooltube.

 

[Texassativa]

It all depends on where your plants like the light. Some plants like it hot while others cold. Try your light at different heights. Find the space where the plant enjoys it most. This might be anywhere from 5" to 2'. It's hard to tell you the exact height you need, due to your light and growroom design. Everybody uses differnet methods. Theirs is not the same as yours. Good luck with your grow!

 

[bostrom155]

This is what i'm trying to figure out too, I want to keep 8 plants under a 400. but wonder if I could do it better.

 

[Maj.PotHead]

a cool tube like mpro has or a air cooled hood with glass like sport farmer also has is the best ways to grow. if ya dont use these methods good passive fresh air intake at bottom and strong exhaust at top oposite side to provide proper ventilation. proper ventilation is a key factor in keeping grow temps down or like sport farmer mentioned about the light on back of hand method. im unsure how long a MH bulb takes to reach full operating temps but hps take 1-1.5 hr's after this time when light is at operating temp. take the back of your hand carefully dont burn yourself and place it just below the bulb now drop it untill it feels comfortable. if it's to hot for your hand it will be for the plant also. here is a chart to use as a general guide

 

[bostrom155]

I don't like it when the bulb to plant distance exceeds around 12-15 inches for a 400HPS

 

[Jnugg]

No glass sheild,a 400w HPS.I use a 4" 170cfm inline exhuast fan,It is setup to bot cool the light and ventilate the cab through the reflector.Rightnow I could keep my tops about 6" from the light but keep the light about 10 " above plants just to be safe.