Correct light distance

T

thekman1964

Active Member
Hi all,
I have two plants growing under a Blackstar 135w LED. Thankfully both girls are budding OK, well sort of.

I reckon I am about 4 weeks from harvest, so I was wondering what is the best distance the lights should be from the plants? Also, which is the best way to tell if LED lights are too close or far from the plant?

Thanks heaps.

TKM
 
A

actont

Active Member
If it burns the back of your hand enough for you to want to move it after 5 seconds..its to hot..if not plants won't mind.
 
topfuel29

topfuel29

Well-Known Member
you should be able to put your LED's as close you your plant as you want. They have really no heat.
What ever works good for you.

Good Luck on your grow.
 
dbkick

dbkick

Well-Known Member
the angle lenses used would probably determine height. personally with blackstars I say hang them 20 feet above or so where the dude upstairs is growing weed and run HID yourself.
 
MYOB

MYOB

Well-Known Member
You want to find the point where you get maximum footprint coverage and maximum light intensity.

It doenst make sense to put a light right on top of the plants and lose coverage on the perimeter. It also doesn't make sense to put high for maximum coverage and losing all the intensity.

The back-of-the-hand thing is too simplistic and a bit dated as a gauge. It was mainly used as a guide when open reflectors were used with HOS and MH bulbs.
 
JonnyAppleSeed420

JonnyAppleSeed420

New Member
If you watch your new growth you can actually see chlorophyll bleaching. It looks like stripes on the leaves if left to long. Most of the LED'S have instructions on how far depending on the wattage and intensity of the bulbs used. Generally 8-12 inches would be max. for most on the market today.
 
ThePerfectGrow

ThePerfectGrow

Member
thekman1964 said:
Thanks for that, but with LED's I could have my hand near the lights forever.
Click to expand...
which means you can put as close as you want and dont have to worry about burning but I still wouldnt let them touch! Just allow a few inches for growth spurts during early flower stretch period!
 
JonnyAppleSeed420

JonnyAppleSeed420

New Member
ThePerfectGrow said:
which means you can put as close as you want and dont have to worry about burning but I still wouldnt let them touch! Just allow a few inches for growth spurts during early flower stretch period!
Click to expand...
Bleaching chlorophyll in the leaves can and does happen with LED's. The 3-5 watt diodes can be pretty intense. Your manufacturer should have specific distances for the unit you have. Personally I would not go any lower than 7 inches from the tops.
 
ThePerfectGrow

ThePerfectGrow

Member
JonnyAppleSeed420 said:
Bleaching chlorophyll in the leaves can and does happen with LED's. The 3-5 watt diodes can be pretty intense. Your manufacturer should have specific distances for the unit you have. Personally I would not go any lower than 7 inches from the tops.
Click to expand...
I stand corrected Jonny! Light bleaching who'd a thunk it!
 
Jimmy Luffnan

Jimmy Luffnan

Well-Known Member
I actually use a pretty funny yet innovative method of light/heat distance ^^
I doubt anybody else does this (apart from my peers which I have shown) tee he

Do remember when you were a kid and you would write invisible messages on paper with lemon juice and lean it against the toaster to reveal the message with heat?

Well I actually do this for distancing with HID bulbs... sounds a little unorthodox... but hear me out :P
You take a piece of A4 paper and a syringe (if you use them for chems) and draw a line down the middle from end to end with the lemon juice.

Hold the piece of paper edge up and straight out from the bulb like you would a measuring tape.

You will see the line go very dark brown near the bulb and get lighter as it gets further away.

Find the best "brown" shade that works for you and ta da.... that is your heat distance =D

Reason I use this method is because your ability to accurately use the back of your hand (burn technique) varies on many factors depending on your hand that day.... but the 'invisible paper' is nearly always correct ;)

Just throwing it out there ;)

Cheers Jimmy.
 
ThorGanjason

ThorGanjason

Well-Known Member
Jimmy Luffnan said:
I actually use a pretty funny yet innovative method of light/heat distance ^^
I doubt anybody else does this (apart from my peers which I have shown) tee he

Do remember when you were a kid and you would write invisible messages on paper with lemon juice and lean it against the toaster to reveal the message with heat?

Well I actually do this for distancing with HID bulbs... sounds a little unorthodox... but hear me out :P
You take a piece of A4 paper and a syringe (if you use them for chems) and draw a line down the middle from end to end with the lemon juice.

Hold the piece of paper edge up and straight out from the bulb like you would a measuring tape.

You will see the line go very dark brown near the bulb and get lighter as it gets further away.

Find the best "brown" shade that works for you and ta da.... that is your heat distance =D

Reason I use this method is because your ability to accurately use the back of your hand (burn technique) varies on many factors depending on your hand that day.... but the 'invisible paper' is nearly always correct ;)

Just throwing it out there ;)

Cheers Jimmy.
Click to expand...
I love innovation, but I love unorthodox innovation even better.
 
Jimdamick

Jimdamick

Well-Known Member
I would not go closer than six inches. I had mine about 2 inches once, woke up in the morning and 1 plant had grown into the light and I ended up with a bleached and burned cola which took forever to grow back.
 
JonnyAppleSeed420

JonnyAppleSeed420

New Member
ThePerfectGrow said:
I stand corrected Jonny! Light bleaching who'd a thunk it!
Click to expand...
I had set up a room for a gentleman who purchased almost $20,000 on LED lighting, we went through the set up with him, like always, and let him at it. Two months later He called me and I went over, he had brought his lighting right down on their heads, the wall lighting was touching the sides and they looked like a tiger...the whole thing! We thinned his room, removed 5 plants and repositioned the lighting and within 2 weeks they looked like they never skipped a beat! JAS
 
Adjorr

Adjorr

Well-Known Member
LEDs using multiple bulbs need enough distance between the light and the plant for all the spectrums to mix together, 1-2 feet is best
 
C

CareStaker

Well-Known Member
For me, no less than 15" away, or the new growth leaves will get this blown-out look. Last run was a different strain, and she could only go to "16.
 
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