Optimum Plant Headroom?

Knally

Knally

Well-Known Member
First time LED user after many years of MH and HPS grows and trying to learn the optimum distance I should keep my lights above my canopy and % of dimmable switch to utilize. The plants are at the end of 2 weeks flower with their canopies at about 3 to 3 and half feet.

Currently I'm running a 400-watt dimmable Timberline COB 3500k at about 75% in a 3x3x6 tent and in a 2nd tent I'm running a 200-watt Crixsun full-spectrum in a similar tent. Temperatures in both tents are low to mid 70's lights on and low to mid 60's lights out and RH 65%-70%.

The HPS lets you know pretty quick if the plants are too close. I did notice some light whitening on the new growth of one of the plants and raised the light and that seemed to help for a little while, but it is quickly getting into the same issue, I think.

I'll post a couple of pics when the lights come on later. Your advice is appreciated. Thanks.
 
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Phytoplankton

Well-Known Member
Yeah, pics will help. LED light height varies by manufacturer, so I’d start with the manufacturers recommendations, then see how the plants react, then adjust accordingly. I’m running a 450w HLG, at 60% about 22 inches above the canopy, 60% humidity, still in veg. You may want to reduce your rh as the buds mature to reduce the chances of bud rot.
 
Rennpappe

Rennpappe

Active Member
Take some measurements with your phone. You can measure ppfd with Photone. You'll have to invest a pound or two however to get accurate LED measurements.
For strong LEDs I'd say 40 - 60 centimeters is OK.
 
Beeswings

Beeswings

Well-Known Member
Check manufacturers recommendations, 24 to 36 inches for my vivosun LEDs. Almost forgot to say your temp seems pretty dang low. LEDs don't have much for infrared radiation so you could be missing out on more vigorous growth. Using a temp gun to check the temperature of the leaves I run around 82 degrees in the tent for a mid 70s leaf temp.
 
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axe007

Member
Knally said:
First time LED user after many years of MH and HPS grows and trying to learn the optimum distance I should keep my lights above my canopy and % of dimmable switch to utilize. The plants are at the end of 2 weeks flower with their canopies at about 3 to 3 and half feet.

Currently I'm running a 400-watt dimmable Timberline COB 3500k at about 75% in a 3x3x6 tent and in a 2nd tent I'm running a 200-watt Crixsun full-spectrum in a similar tent. Temperatures in both tents are low to mid 70's lights on and low to mid 60's lights out and RH 65%-70%.

The HPS lets you know pretty quick if the plants are too close. I did notice some light whitening on the new growth of one of the plants and raised the light and that seemed to help for a little while, but it is quickly getting into the same issue, I think.

I'll post a couple of pics when the lights come on later. Your advice is appreciated. Thanks.
Click to expand...
You need to set dim and height based on photosynthectic proton flex density
Ppfd
You can downlown a app to see how bright you are at during germ, veg, flower
I
 
ProPheT 216

ProPheT 216

Well-Known Member
I have marked where 24 inches from my light is, and also 18 inches. I personally leave my light on 100% all the time and leave it at the same height all the time. I let my plants grow up to the light and start training at 24 inches and try to keep them somewhere around the 24 inches away... staying under the 18 inch mark for sure.

Leave your light turned up and look at your par map and see where you should try to keep the canopy level with training as they grow past it. I only use my dimmer to make it dimmer for me to work around
 
Rocket Soul

Rocket Soul

Well-Known Member
Knally said:
First time LED user after many years of MH and HPS grows and trying to learn the optimum distance I should keep my lights above my canopy and % of dimmable switch to utilize. The plants are at the end of 2 weeks flower with their canopies at about 3 to 3 and half feet.

Currently I'm running a 400-watt dimmable Timberline COB 3500k at about 75% in a 3x3x6 tent and in a 2nd tent I'm running a 200-watt Crixsun full-spectrum in a similar tent. Temperatures in both tents are low to mid 70's lights on and low to mid 60's lights out and RH 65%-70%.

The HPS lets you know pretty quick if the plants are too close. I did notice some light whitening on the new growth of one of the plants and raised the light and that seemed to help for a little while, but it is quickly getting into the same issue, I think.

I'll post a couple of pics when the lights come on later. Your advice is appreciated. Thanks.
Click to expand...
In order for your plants to flourish in high intensity light you need to dial in your environment a bit. You want somewhere around 80-84F temps and the correct rh/VPD for the plants grow stage.
Leds don't give off as much radiant heat or infra red as HID, so you cant grow with them very well if you follow HID environmental and feeding advice. You need a bit more heat, correct vpd, and probably up the feed a bit; lower transpiration means feed needs to be a bit higher than usual.
 
Knally

Knally

Well-Known Member
Rocket Soul said:
In order for your plants to flourish in high intensity light you need to dial in your environment a bit. You want somewhere around 80-84F temps and the correct rh/VPD for the plants grow stage.
Leds don't give off as much radiant heat or infra red as HID, so you cant grow with them very well if you follow HID environmental and feeding advice. You need a bit more heat, correct vpd, and probably up the feed a bit; lower transpiration means feed needs to be a bit higher than usual.
Click to expand...
Thanks for the info. Yeah, the grow is definitely different under the LED's than HID and have new to me strains going so it's more learning with those also. Stuck with feminized photoperiod so it's at least something familiar. LOL I'm satisfied with my grow under the Timberline 400 watt COB but need to replace an outdated Crixsun 200 watt in my 2nd tent. Looking at a Spider Farmer or Mars. Too cold in the tent and not enough penetration like the Timberline.
 
Knally

Knally

Well-Known Member
axe007 said:
You need to set dim and height based on photosynthectic proton flex density
Ppfd
You can downlown a app to see how bright you are at during germ, veg, flower
I
Click to expand...
Thank you. Took your advice and downloaded and an app that simplifies it. They're doing well now.
 
Knally

Knally

Well-Known Member
coreywebster said:
Not heard of timberline. Is that Timber?

400w cree cobs on a 3x3 , nice. Should be good around 24" in flower, further in veg..
But as Rocket said, temps need to be higher .
Click to expand...
Thanks. I added an oil filled heater in between the two tents with the side bottom vents open to allow some heat. Brought up the temps about 5-7 degrees overall. I'll post a pic of the Sleppy OG when the lights come on later. She's sweet and filling out after getting the temps up and the headroom adjusted.
 
Knally

Knally

Well-Known Member
Moflow said:
Yea, Timber did a 400 watt 4 cob fixture using vero 29 v7's. If that is the light.
18" for flowering.
View attachment 5384638

Haven't heard of Timberlake tho.... lol
Click to expand...
Thanks for the information. Yep, It's aTimberline 4 100-watt Vero COBs with 3500K temp. I'm liking it a lot after I got some things worked out. I used HPS for a lot of years in a much larger area. This is different. No, I haven't heard of a Timberlake either. LOL
 
J

joesoap2013

Well-Known Member
Knally said:
Thanks for the info. Yeah, the grow is definitely different under the LED's than HID and have new to me strains going so it's more learning with those also. Stuck with feminized photoperiod so it's at least something familiar. LOL I'm satisfied with my grow under the Timberline 400 watt COB but need to replace an outdated Crixsun 200 watt in my 2nd tent. Looking at a Spider Farmer or Mars. Too cold in the tent and not enough penetration like the Timberline.
Click to expand...
Yep man knownwhat ya mean
My thought for my next grow turn the light up bout 80 percent
Then it's more like a hps have a fan blowing down on to the canopy the heat off it Heat the leaves up a few degrees
 
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