Distance between plants

Get a par chart or head to youtube where growmau5 measure the par of every board. Your threshold without co2 is around 1000. All you need to do is check out the par measurements with your model and get a good estimation on how close to put them. Hope this helps.

 

I've tested my two 380 wall watt LED's at 9" earlier on in my current grow with no issues. Running them at 12-14" in week 5 of flower right now for a bit wider coverage, josh.

 

These plants were stressed with low humidity and organic soil with a high pH.

The light (390 true watt BESTVA) at under 30" was causing too much extra strain and began to bring out deficiency symptoms.
The plants won't stretch either; making the SCROG a slow one.
Nodes half inch apart is ridiculous with a 390 watt light 2 1/2+ feet away. Should also note the room is 2.5 by 5 feet.

I'm not saying Cola Grande is wrong or anything like that; but be cautious because LEDs vary widely on effectiveness. I believe it depends on the ratios of colors along with the type of diode being driven at what wattage.

 

IMO, there is absolutely zero chance that a bestva 390 true at 30" can even remotely contribute to, or cause any, plant health issues.

I'm running two of the exact same LED's (King Plus 2000's) and had them at 9" for a week with no adverse effects. At 8" the plant leaves began canoeing and trying to turn away from the heat.

I cannot think of of any circumstance where light would hurt a cannabis plant. Heat, yes, light, no way.

 

Light absolutely stresses plants out when there is too much of it. Definitely when the plant has other problems and can't utilize the light it is receiving. Anytime a plant has a issue backing off the light offers some relief.

Maybe for the situation I observed being in a 2.5x5 7' high room with flat white paint contributed to the intensity.

Seedlings didn't stretch abnormally from that distance either; under the screen even so call it 48" away from them. What can I say?

Tests by several growers suggest the 2000w performs somwhat like 600-800 watts of HID .

 

Guess we're just gonna have to agree to disagree on the light thing here, alaska.

If a plant is in such condition that light hurts it, there's probably a whole lot more than that to worry about.

Grow em big!

 

I had a Wonder Woman under two 3000k Q120 boards at about 9 inches ,(replaced a Viparspectra in mid flower). The buds all started foxtailing so I backed the light up to ~15" and they finished fine. The two Q120s were obviously much more than the VS450 at the same height.

 

Photosynthesis under artificial light: the shift in primary and secondary metabolism

"If lighting is too weak, photosynthesis cannot work efficiently and etiolation symptoms appear [5]. However, excessive light generates oxygen radicals and causes photoinhibition. Both phenomena strongly limit primary productivity [6]."

I like science.

 

Is that specifically in reference to cannabis plants?

And, remember, you can believe 90% of what you read on the www - 50% of the time.

 

You can read the article yourself to determine if it is legit.

Doesn't have to be cannabis specific in my opinion, but the study does use tomatoes (and lettuces) which from what I understand is similar enough to cannabis. They can be grafted together. (Same with potatoes! Yum!)

This whole light thing is quite complex. I suggest just doing your own research. Plenty of studies on this subject new and old.

The article has interesting reading about how different colored LEDs affect taste and even appearance of how plants grow. It also discussed the relationship between red, blue, and green led diodes; and how they work together for plant functions.

 

Cannabis cannot get enough light.!!
I have never had an outdoor or indoor plant get light burn.!! (only ever used HID and Floro)
However, the new LED's may have certain diodes producing a certain light spectrum,
this might cause parts of plants to get a toxic amount of 'light' from those diodes.!

light burn on cannabis plants is not light burn, it is heat stress.!
place your thermometer 9" from your light, is it 85+ degrees.?
if so it is too hot, either raise the light or provide better ventilation.!!

 

I disagree, these LEDs run very cool temperature wise compared to the lights they replaced but put out much more light. You would never have too much light outside, as the sun is only so close to the earth. However, indoors you can produce more light than the sun which can overwhelm the plants natural growth processes. I also expect there will be much variation on tolerance to light from strain to strain.

This is a good article on light stress:
PSA: Too Much Light?! | Grow Weed Easy