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How Does Light Distance Influence Plant Growth?

snakeman69er

New Member
ok, so ive been reading forums on many different sites, and ive learned a hell of alot!

But with this rapid influx of knowledge comes zero first hand experience...

i also have a learning disability and often struggle to understand, and use the knowledge properly

I've struggled hard with this endeavour and lost alot of seedlings with stupid mistakes.. bad soil, over watering, root bound plants... cutting off leaves and shoots....cfls in a rubbermaid

just about every mistake that can be made..ive made it (but i was gifted a few hundred seeds of top notch genetics so its not a big loss.. just time and hydro, and well, my pride too)

ive learned alot and overcome alot most of issues...

but one issue i dont understand is light hight... and theres ALOT of conflicting data!!

i know alot about lights... different types of grow lights.. par, lumens/lux, kelvins, wattage, "inverse square law"...

what i want to know is what hight to put my 600 watt light ( 3x3 tent) in early_mid veg

i know enough not to allow intense light to fry my plants... and i realize that in flower i want them as close as possible without exceeding usable light saturation and avoiding heat and light bleeching

ive read that most people start high with seedlings, and lower lights gradually over the course of a week or so to optimum lux/lumens (the gradual lowering allowing plants acclimate to light intensity)

ive also read that keeping your lights close will stunt overall plant hight, and you'll end up with like a much smaller plant with a shit ton of really closely spaced nodes that end up yielding alot less then a plant at optimum hight/node ratio

ive read that leaving my lights higher will encourage my plants to grow into the space and create a better canopy/hight ratio

can anyone help illuminate this issue for me?
 

Islandgrow

Well-Known Member
ok, so ive been reading forums on many different sites, and ive learned a hell of alot!

But with this rapid influx of knowledge comes zero first hand experience...

i also have a learning disability and often struggle to understand, and use the knowledge properly

I've struggled hard with this endeavour and lost alot of seedlings with stupid mistakes.. bad soil, over watering, root bound plants... cutting off leaves and shoots....cfls in a rubbermaid

just about every mistake that can be made..ive made it (but i was gifted a few hundred seeds of top notch genetics so its not a big loss.. just time and hydro, and well, my pride too)

ive learned alot and overcome alot most of issues...

but one issue i dont understand is light hight... and theres ALOT of conflicting data!!

i know alot about lights... different types of grow lights.. par, lumens/lux, kelvins, wattage, "inverse square law"...

what i want to know is what hight to put my 600 watt light ( 3x3 tent) in early_mid veg

i know enough not to allow intense light to fry my plants... and i realize that in flower i want them as close as possible without exceeding usable light saturation and avoiding heat and light bleeching

ive read that most people start high with seedlings, and lower lights gradually over the course of a week or so to optimum lux/lumens (the gradual lowering allowing plants acclimate to light intensity)

ive also read that keeping your lights close will stunt overall plant hight, and you'll end up with like a much smaller plant with a shit ton of really closely spaced nodes that end up yielding alot less then a plant at optimum hight/node ratio

ive read that leaving my lights higher will encourage my plants to grow into the space and create a better canopy/hight ratio

can anyone help illuminate this issue for me?
You make some very good points and would love to see peoples thoughts on this subject as well . I know if the light is too high it would cause the plant to reach for the sweetzone between 18 to 30 inches from the light. .I think that is the sweetzone for a 600watt
 

BakinOnDaFarm

New Member
Mine seems to like 20"-24" 4x4 tent 600w mh/hps.
Moved it closer and it really dries them out. Starts to burn leaves. HID lights emit a crazy amount of heat. At least to me anyway lol.
 

KingJoe83

Grow Journal of the Month: July 2017
My lights at vege auto s led light s pro mix tent ate 26" from seed then veg 20 ish 22 I keep them. Flower 15" ish understand every answer may different as to environments band kind of lighting used. And area. I also measure from top of plants to base of light.
 

r249124

New Member
Hi

I use a 900 watt viperspectra led once germinated I had them at about 36 inches for a few days. Well I'm on day 9 now and I've just moved the light to 24 inches give or take an inch !

I think anymore than that with a 900 would not be good but I'm not an expert etc

My plants are very healthy 9 days in so far [emoji1531]
 

Buzzer777

New Member
My LED Manufacturer sent this for LEDs though..
LEDs can bleach out buds if too close..

"450W LED Grow Light Full Spectrum
for Indoor Plants Veg and Flower - Dual Growth/Bloom Switch Daisy Chain Following the product manual, please pay attention to the NOTICE before you start use. I really hope it may help you a lot.

Advised light above plants for seeding,growth and flowering time:
Germination-------------24-30 inches
Vegetable -- --------18-24 inches
Flower------12-18 inches

Advised Lighting Time:
Vegetative Stage: 18-20 hours on,4-6hours off; Flowering Stage: 12 hours on,12hours off. Veg: 18/6 or 20/4; Flower: 12/12

our new series lights have both growth and bloom switches.
On growth stage, keep the growth switch on.
On flowering stage, keep both veg & bloom switches on."
 

luckiestman13

New Member
A better way to control stretch is with the temperature of the light. Or kelvin or color.

All lights can bleach plants.

You mentioned you had a 600 w light? 600 what? LED manufacturers are notorious for selling under driven fixtures. Or is it HPS?

Pacific light concepts has the best price point for LEDs this week! :) amazing product unlike that plurple you see in some LEDs.
 

snakeman69er

New Member
wow, ya sorry.. i thought I had included the details but after re reading i guess i screwed up


thanks for the info everyone!! appreciate it...

i have a 40"x40"x 6.6 foot tent, lighted by a 600 watt cooltube, with 6"can fan blowing air from inside tent through the tube, reduced to 4" insulated semi rigid aluminum ducting (blows hot air right out my window)

i have ducting to seal the loop (so to speak) and pull air from outside tent though cooltube..just havent hooked it up yet....

the light is run by a duel MH/HPS digital dimmiable ballast...

i have another 6" can fan in the ceiling of the tent for extraction in the event that i close the loop and cool my light with air from outside tent (havent used it yet though)

i dont have any smell control yet.. but will soon... just tripped to flower..so i know im gonna need it soon

im using wallmart potting soil with perlite in 7 gal fabric smart pots

i actually did figure stuff out in the intervening months since i wrote this post.... but i really appreciate it guys

as soon as i figure out how to upload pix i will!!

everythings going amazing!!!!!
 

r249124

New Member
Just some guidance n updates on LED distance n performance regarding my plants responses.

I started with 30 inches away and after 2 weeks I kept it at 24 inches n now 4 week mark maintaining 20-24 inches distance from the top of the plants n my plants are exploiting and I've got flowering sites on my10/11 week autos after 26/27 days off my 900 watt Viperspectra [emoji123]
 

r249124

New Member
Just some advice I have the led light 20 inches above the tallest plant now I have to move it but will it still penetrate the rest of the canopy? As some are shorter etc
 

r249124

New Member
Hi Snakeman69er

I wasn't I found yours useful so thought I'd add to it that's all mate no worries

I've moved mine down to about 15 inches following advice from my journal ! I had to move the plants pull it down n oh the wAy now I have good coverage on the canopy. But I don't want to burn the bud etc

If it's okay with you I'll add to yours regarding the effects on light influence for yourself n others or I can just leave it
 

Scientific

New Member
I used to work for a PhD engineer who in situations like this would say, "Looks like we're going to have to take some measurements."

A $16 lux meter from Amazon will enable you to get your plants in the sweet spot of about 50,000 to 60,000 lux. (It works for every kind of light except blue/red "blurple" LED grow lights.) Everything else is pretty much folklore and best guesses.
 

handjive4mota

New Member
hey there snakeman69, thought you were confused before you started growing? your brain will be doing flip-flops 24/7 thinking
about this stuff. After a few months you will not be sure about anything, but you sure will have a lot of information to process.
 

r249124

New Member
Light distance examples 2,3 and 4 weeks remaining for n these 900 watt viperspectra led

Had them at 24 inches ,18 and 10 inches from canopy
 
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