Lighting What about light stress with too much Autocob goodness?

[lunarman]

I know we have talked about how much COB lighting to use. And distance from light to canopy. And how many autocobs per plant. And what affect this has. With lots of positive things being said about how less is more. For example, keep the light a respectful distance away and your plants will love you back more like you'll get more frost.

But what about too much autocob lighting and light stress and what does that look like? I have one plant that can be quite large for an auto. DP Think Different. A couple of weeks ago when she started to flower (at a height of about 22 inches) I put an extra autocob on her for a total of 2.

The entire plant is a pale green color now. I'm not sure when this happened or why. This sort of thing is gradual. This sort of thing is not an exact science or is it always easy to know exactly what an issue really is. But I think I can rule out nutrients because the nute schedule I'm using is working great for other plants.

Tony from Dutch Passion said it could be pheno differences. There are a lot of factors as well that could cause this. But he said the thing that jumps out at him the most is light stress.

I don't get any leaf curling from heat. I do have HPS up in the roof of the tent that I use for lighting when flowering and for heating. But I have lots of fans circulating air. I have cold air in. I don't have any heat stress for sure right now. And I have 1 autocob per plant. But I was able to put two autocobs on this plant and have been for a couple of weeks. I'd say 24 inches above the canopy. But I don't really understand light stress and what that looks like when it comes to autocobs/cobs.

So have a look at these pics and tell me if you see signs of light stress.

Top of main cola



Top of plant


Two pale leaves next to a green one from another plant in the tent.


Close up of pale leaf.

 

[lunarman]

Couple of more pictures to give a different perspective and contrast with two Mephisto Skywalkers that have been getting the same nutes but are much greener. They are 11 days younger. And have never had 2 autocobs directly on them.



And this is the tent space from the door. There are 2x600 watt HPS cool tubes down the middle of the roof. And autocobs hang down the HPS lights on each side of them. I can put 1 or 2 autocobs on each plant but generally only put one. And I can turn on the HPS or not. I mostly leave them on for heating in the winter.

 

[CoviklaFlaire]

Try to make your cob higher from canopy..

 

[AutoWonders]

I put an extra autocob on her for a total of 2.

I recently attempted a two autocob one plant test and it was far too much lighting. Those leaves curled up and were ready to canoe the hell away from me at top speed. Right now I am testing an Autocob with reflector and one without. Same strain.They are in veg and the light with reflector is pulling away from the non reflector. I'm doing the same thing for two other plants, but they are not the same strain. It seems that reflector use for veg is the way to go. I started at 30" from seedling and am now down to 25". Hopefully I might be able to eek out a few more inches lower.

I also did one Autocob for two plants and though it was fine, one Autocob per plant is the sweet spot.

 

[lunarman]

I recently attempted a two autocob one plant test and it was far too much lighting. Those leaves curled up and were ready to canoe the hell away from me at top speed. Right now I am testing an Autocob with reflector and one without. Same strain.They are in veg and the light with reflector is pulling away from the non reflector. I'm doing the same thing for two other plants, but they are not the same strain. It seems that reflector use for veg is the way to go. I started at 30" from seedling and am now down to 25". Hopefully I might be able to eek out a few more inches lower.

I also did one Autocob for two plants and though it was fine, one Autocob per plant is the sweet spot.

Have you ever seen light stress where it's pale green like mine is?

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[Hippy_BiotabsF70]

I know we have talked about how much COB lighting to use. And distance from light to canopy. And how many autocobs per plant. And what affect this has. With lots of positive things being said about how less is more. For example, keep the light a respectful distance away and your plants will love you back more like you'll get more frost.

But what about too much autocob lighting and light stress and what does that look like? I have one plant that can be quite large for an auto. DP Think Different. A couple of weeks ago when she started to flower (at a height of about 22 inches) I put an extra autocob on her for a total of 2.

The entire plant is a pale green color now. I'm not sure when this happened or why. This sort of thing is gradual. This sort of thing is not an exact science or is it always easy to know exactly what an issue really is. But I think I can rule out nutrients because the nute schedule I'm using is working great for other plants.

Tony from Dutch Passion said it could be pheno differences. There are a lot of factors as well that could cause this. But he said the thing that jumps out at him the most is light stress.

I don't get any leaf curling from heat. I do have HPS up in the roof of the tent that I use for lighting when flowering and for heating. But I have lots of fans circulating air. I have cold air in. I don't have any heat stress for sure right now. And I have 1 autocob per plant. But I was able to put two autocobs on this plant and have been for a couple of weeks. I'd say 24 inches above the canopy. But I don't really understand light stress and what that looks like when it comes to autocobs/cobs.

So have a look at these pics and tell me if you see signs of light stress.

Top of main cola

View attachment 876900

Top of plant
View attachment 876899

Two pale leaves next to a green one from another plant in the tent.
View attachment 876901

Close up of pale leaf.
View attachment 876902

Personally I don't see any signs of light STRESS mate. Maybe you just need to up the nutes to account for the severe amount of light you have in there?

But those leaves / plants are not stressed as such. No tacoing. No raised edges/fingers. Just looks hungry as fook to me?

Just my opinion though.

 

[Hippy_BiotabsF70]

How much is too much depends on the plant, the environment and how hard you're feeding.

I have seen one plant under 200w of cobs plenty of times, with no stress. I have also placed cobs way too close to plants and then you'll see light stress!

 

[lunarman]

How much is too much depends on the plant, the environment and how hard you're feeding.

I have seen one plant under 200w of cobs plenty of times, with no stress. I have also placed cobs way too close to plants and then you'll see light stress!

Tell me what does that cob light stress look like? Just curling/tacoing? No color change? Bleaching?

Thanks for chiming in man. Its stressful when you see something wrong with a plant and you take pictures and provide info and everyone has a different opinion on what is wrong. I hate the mysterious plant issues!!!!

 

[bakEQuatorial]

Tell me what does that cob light stress look like? Just curling/tacoing? No color change? Bleaching?

Thanks for chiming in man. Its stressful when you see something wrong with a plant and you take pictures and provide info and everyone has a different opinion on what is wrong. I hate the mysterious plant issues!!!!

I started my cobs from 100cm to 85cm to 75cm and then just less than 50cm. 425W highest draw from wall, 6 cobs in total. I need to stress that mine are not autocobs but are China cobs. On average, each light outputs 70++W.

I wanted to let them stretch a little more so for the past few days, they are around 60cm (2 ft).

I noticed much lighter colored new growths but felt it was normal. They grow big and fast under the cobs. So probably needs to be fed more is what I thought. My humidity is very high so they dry slow. A soaked 5 gallon pot (filled to 3/4 only) at week 3-4 takes 5 whole days to feel lighter but top soil still moist. Therefore, can't feed as often. So its not far fetched that its nutrient related.

As a newb, i base stress only by obvious symptoms. I do get some random curling but as long as they look healthy in general, i don't know what else i can do?

My closest distance in inches is around 18 inches. Early vegging too. Never saw obvious stress. But I do suspect it affects vertical growth a little cos after i raised a few inches, they took off immediately.

There is just too much variables to consider. Unless a master does a comparison for us newbs, a lot will remain speculation.

Like for my case, its outdoor on a balcony. My vicinity has lotsa plants/ trees. I feel that my plants grow a lot at night. It should be due to the extra CO2 at night as im surrounded with plants/trees. So i think environment is a huge factor. Perhaps with more CO2, more air movement, longer light hours, more nutes, the plants can take more light compared to a plant that has lesser?

Take my ramblings with a grain of salt cos im a newb. I subbed this thread almost instantly cos i wanted to learn more too. Looking forward to some masters providing enlightenment!


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[Hippy_BiotabsF70]

Tell me what does that cob light stress look like? Just curling/tacoing? No color change? Bleaching?

Thanks for chiming in man. Its stressful when you see something wrong with a plant and you take pictures and provide info and everyone has a different opinion on what is wrong. I hate the mysterious plant issues!!!!

IMO light stress looks like tacoing (whole leaf folded inwards like a taco) and the serrated fingers on the leaf edges being raised up. Bleaching I think would be an extreme yellowing.

To me yellowing is fast growth due to lots of light, but not quite enough nutes (or possibly certain nutes/elements). People say cobs "suck" calcium out of plants. I personally don't agree. I think plants just grow very fast under cobs and need lots of calcium to keep up. Calcium should be in your nutrients, so upping the feed level should do the trick. They will need more of everything to keep up with growth.

But for me, a plant lacking in calcium is not light stress caused by cobs. It's a lack of calcium. Etc.

I would be careful of assuming it's not nutrient issues because the other plants on same nutrients are ok. All plants are different. One has two cobs above it. Etc etc. Assumption is the mother of all f*ck ups!

Please also don't assume anything I say is correct. I can only report my own experiences with cobs.