How many inches of space should be in-between your LED lights and your plants ?

[popolino77]

My tent is 36 inches tall i have my led lights chained up high in my tent there is only about 2 inches of space in between my led lights and the roof of my tent, i had my led light about 27 28 inches from my plants. My plants are 13 days old above ground they grew good for the first 3 days and then they almost completely stopped growiing, i decided to put my flower pots on top of shoe boxes, now my led lights are 22 23 inches from my plants. I am using a 300w 140 true watt led light and a 24w 14.8 true watt led grow bulb, is there still to much distance in between my led lights and my plants ? Or is 22 23 inches good distance ?

 

[lexort420]

Ive read plenty of places that typically 12inches above the top of the plants is what led growers typically keep it at.

 

[popolino77]

Ive read plenty of places that typically 12inches above the top of the plants is what led growers typically keep it at.

There is way more then 12 inches in between my plants and my led lights i did not take a ruler and measure but i would say there is at least 20 inches, i read that 16 to 30 inches depending on the led's watts

 

[OlderGrower]

I think it depends on what results you are looking for. One thing to keep in mind is when you flip to flower they will continue to grow in height. Each strain is different but as a general rule you can figure a multiplier of 1.5 for pure Indica, 2 for hybrids, and 2.5 for pure sativa. So if you flip to flower and your hybrid is 2 foot tall it will be 4 foot when done. This being said with a small tent I would be flipping her while she is fairly short. The easiest way to determine how much grow area you have to work with is with the light as high as you can take it, measure from the lens down to the top of the pot your plant is in. This # minus 6 inches is your maximum grow height.
Now for the height of the light above your canopy.
With the tape in one hand take your other arm and put it under the light. Hold it between 6 to 12 inches away from the light with the most sensitive part of your forearm aimed at the light. Pick a distance and hold your arm there for a few minutes. If it becomes uncomfortably warm, you are to close. When it is warm but not uncomfortable, measure from your forearm to the light. That spacing should work for you. I just measured my LED and on my stand alone plant the closest top is 9 inches away from the light.

post a few pictures if you can, that would make helping you a lot easier.

I would suggest 9 to 12 inches till you start seeing growth, and never further away then 18 inches with that small of a light.

 

[OlderGrower]

Ive read plenty of places that typically 12inches above the top of the plants is what led growers typically keep it at.

Most suggest 12 to 18 inches though I have seen on a few un named LED web sites (Non-sponsers) saying to get max coverage they suggest 6 feet. Which I have to call a BS on.

 

[popolino77]

Most suggest 12 to 18 inches though I have seen on a few un named LED web sites (Non-sponsers) saying to get max coverage they suggest 6 feet. Which I have to call a BS on.

Now that i put my plants on shoe boxes 5 inches off the ground closer to my lights my tent tempearture is 4 farinhight cooler , is this normal ? Or is there some thing wrong with my lights ?

 

[popolino77]

I think it depends on what results you are looking for. One thing to keep in mind is when you flip to flower they will continue to grow in height. Each strain is different but as a general rule you can figure a multiplier of 1.5 for pure Indica, 2 for hybrids, and 2.5 for pure sativa. So if you flip to flower and your hybrid is 2 foot tall it will be 4 foot when done. This being said with a small tent I would be flipping her while she is fairly short. The easiest way to determine how much grow area you have to work with is with the light as high as you can take it, measure from the lens down to the top of the pot your plant is in. This # minus 6 inches is your maximum grow height.
Now for the height of the light above your canopy.
With the tape in one hand take your other arm and put it under the light. Hold it between 6 to 12 inches away from the light with the most sensitive part of your forearm aimed at the light. Pick a distance and hold your arm there for a few minutes. If it becomes uncomfortably warm, you are to close. When it is warm but not uncomfortable, measure from your forearm to the light. That spacing should work for you. I just measured my LED and on my stand alone plant the closest top is 9 inches away from the light.

post a few pictures if you can, that would make helping you a lot easier.

I would suggest 9 to 12 inches till you start seeing growth, and never further away then 18 inches with that small of a light.

My plants are autoflowering i dont know if that information applies to me. I thought the further away your plants are from the light the more they grow because they stretch to reach the light isn't that true ?

 

[popolino77]

Now that i put my plants on shoe boxes 5 inches off the ground closer to my lights my tent tempearture is 4 farinhight cooler , is this normal ? Or is there some thing wrong with my lights ?

Im such a jack ass i didn't have my termometer inside my tent

 

[Atulip]

Depends on the led, but I keep mine around 12 inches above unless I need wider coverage or seedlings, then 18 inches. At around 6 inches I start seeing light stress.

 

[OlderGrower]

My plants are autoflowering i dont know if that information applies to me. I thought the further away your plants are from the light the more they grow because they stretch to reach the light isn't that true ?

While it is true that plants will stretch more when placed further from the light (to a point), is stretching what you are really looking for at this phase of development? Closer receiving a higher PAR count they will stretch less but develop more nodes in a closer area producing a bushier plant in the long run. I am pretty sure plants require the same amount of PAR lighting levels even if they are an auto but may I suggest you ask Atrain over in his thread, "myth busting auto flowering plants" He truly is an auto flowering guru and can set you straight on Auto's.
My only point here would be, a plant is a plant is a plant is a plant, auto or not. They all breath in Co2 and exhale Oxygen. They all require water and nutrients. and they all require light to produce the foods they need to grow big and strong. I am pretty sure the only difference between an auto and a photo plant is one will go into flower automatically no matter how many hours of light it receives where as a photo plant you have to trick it into believing it is time to flower by switching from a 18 on 6 off light schedule to a 12 on 12 off or 11 on and 13 off lighting schedule. They all still need the same amounts of the rest in order to grow healthy.

Again check out the auto threads on the site, they are the real experts when it comes to autos but I am pretty sure what I have told you is pretty much what they will tell you too, but like I said, please do check. I am old like my name clearly states and I have missed stuff before.

 

[OlderGrower]

Depends on the led, but I keep mine around 12 inches above unless I need wider coverage or seedlings, then 18 inches. At around 6 inches I start seeing light stress.

I would say that is a good general rule of thumb way to approach this. Though I am pretty sure the actual power of the LED fixture and sense type would skew the rule. Example would be if you had a 80 watt LED I believe you could get it closer to a plant then say a 650 watt LED without stressing the plant as much. I know when driving at night I am much less stressed when a car is approaching with standard head lights on , then I am when I see those bright ass blue ones on, or when they have their brights on. Kind of the same line of thinking. More power, a little further away to get the same results.