Light bleaching?


This is a ilgm CW plant about 1month old. The lower leaves are showing some yellowing from a nitrogen deficiency. I Upped my N ratio and have kept the plant happy on that front. I also recently switched from my old 600w MH to a 320w hlg quantum board build. At the time of switching lights I had the quantum board about 22” above the plants. The other 2 plants I have at the same age are GL and CD, both of which have not displayed the same marks as CW.

Any ideas?

@Countryboyjvd1971 @Tylan @MattyBear @Donaldj @Sirsmokes @peachfuzz @dbrn32


Sounds like N deficiency like you thought. The QB’s make them hungrier than normal


Pictures in natural light would help.

My plants are 9" from my fixture with no light bleaching.


Here ya go

That’s in front of my dining room window. I had transplanted them to their final homes yesterday and watered to runoff. I was figuring I would let them have at the new soil a bit and see how she fares before hitting her with another feed.


Yea it looks bleache’d but I’m not sure you would think that the bleaching would be affecting the top growth I’m assuming thats close to the light


@garrigan65, what do you think?


LEDs are tricky when trying to figure out light height… not sure what to make of it… :thinking:



Looks like light bleaching to me as well, although I wouldn’t expect it to happen at that range either. Although it could seem more possible if those leaves were already damaged some.



Light Burn,

Problem: Your cannabis plant can only withstand a certain amount of light. After a certain point, your cannabis will start turning yellow or otherwise exhibit signs of stress on the leaves near the sources of light and/or heat.

How far away do I keep grow lights from my plants?

Light burn usually causes yellow leaves at the top of the plant directly under the grow lights (though it can appear on older leaves that have been exposed for a long time).

This light burned leaf is not happy…

Sometimes the first sign a plant is getting too much light is all the leaves start pointing up, (though sometimes you don’t see any symptoms until the yellowing starts)

Example of a cannabis plant that is getting too high levels of light so all the leaves are pointing up
With light burn, often the inside veins stay green. Yellow leaves won’t fall off or be plucked off easily, unlike a nitrogen deficiency where leaves fall off on their own


That’s what I originally thought. It happened to the largest fan leaves a node or two down from new growth. I wonder if it happened to the largest fan leaves because they have the most surface area, therefore absorbing too much before reacting? Idk. I raised the light a couple inches and next time I add light or add a plant to this tent I may dial back the wattage to the board and slowly work it up to 100%. We shall see


Thanks for the knowledge drop!


That plant had previously suffered a bit from N def. but i staved it off before it could reach any upper leaves. Maybe strain specific? As the other two plants of different strain didn’t display any signs. Too many variables I suppose to be able to confidently narrow it down, but I’ll proceed with a bit of caution either way. Thank as always!


I know, tell me about it lol. Ya live, ya learn… :wink:


Thanks for tagging @garrigan65 in from the apron my friend


That’s a reasonable expectation. Like you said, a lot of variables to consider.



Your very welcome on all counts
And there`s my friend again. @dbrn32
lmao. How ya doing…Got me again. Lol


Doing well amigo, how are you?


Getting rained on a the moment…lol


Ha, you replied to yourself and I missed it sorry. Hopefully you’re all dried out by now!