Lime green leaves - light stress and recovery

Hi, new forum member here. Lookin for some help.

I’m in day 27 of flower. About 4 days ago, all of the uppermost leaves closest to the light turned really yellowish lime green. I could tell it was light stress, all of the leaves on the layer just below were fine, as were the ones in the corners of the tent. I backed the light (1000w HPS) off from about 20” to about 28” (I’m at the top of the tent now)

Around that same time, I also applied a feed really heavy in P, which I’m thinkin may have caused lockout of S and Zn. I’m also slowly dialing down temp & co2 at this phase.

Other than the lime green leaves, the plants look great.

Are these light bleached leaves a concern? Will they return to a normal shade of green now that I backed the light off? Should I consider dialing back the light to 750w?

Any knowledge or tips would be greatly appreciated.

I’ll take some photos tonight - HPS is on right meow.

Without photos hard to say but if you do think it's lite burn I'd turn the light down immediately and put the damage plants in the corners if possible, then I'd reassess in 24 hours, pictures will help you
-good luck

Thanks Beachwalker. Turning down my light is NOT what I want to be doing right in the middle of flower stacking though, ya know?! I will obviously if I need to but damn.

Why is this happening now? I’ve been running the 1000w since early veg. Is it because of the decreased temps & co2? It’s around 77f, 57%rh and 700 ppm right now.

Thanks again for responding. I’ll post pics tonight. My lights go off at 7pm EST.

Photo of 2 leaves I just pulled. Large one is the afflicted one. Small one is “normal” color.

Turning down for 12 to 24 hours isn't going to affect anything it's going to help your plants if you indeed did burn them

My plants are little too tall, my thousand Watts at the top of my tent but still a little close, had to turn it down to six hundred, it's just a thing, next time won't let em get as tall

Way I see it I can risk injuring my plants like you feel you may have done, or I can keep them healthy and probably save some electricity at 600w, while still getting close to the same yield because they're not injured, but that's just my way of thinking, hope it works out for you! good luck

That don't look like heat stress to me, I'm not sure if it's like bleaching or not but with heat stress the long edges canoe up, maybe somebody else will have your answer ?

Was it only faded at the top of the plant nearest to the light?
Have you checked your ph? That little leaf really looks too dark imho. A shade somewhere between the two would be ideal.
Also excess light WILL hurt your yield.
Good luck mate.

pH of runoff was 6.4. It’s been steady. Here’s better pics. Sorry some are out of focus, I hate being in there during lights out!

Don't go in there during lights out especially taking flash pictures (or for almost any reason for that matter) ..nice-looking canopy..!

Is that yellow patch directly under the bulb??
Whats your ppm?
6.4 is probably pushing it just a touch too.

Beachwalker said:

That don't look like heat stress to me, I'm not sure if it's like bleaching or not but with heat stress the long edges canoe up, maybe somebody else will have your answer ?

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Heat’s been under control. Was 79-82f while I was really pumping the co2, now I’ve been keeping it at 76-78f with reduced co2, (around 600-800ppm)

I’m assuming if it IS light stress, they won’t necessarily return to a normal color. I did raise the light 8 inches since this happened. The leaves of even the limey ones are “praying” slightly, which they were not doing before I raised the light.

I will still consider dialing down to 750 watts. Thank you both!!

Beachwalker said:

Don't go in there during lights out especially taking flash pictures (or for almost any reason for that matter) ..nice-looking canopy..!

Click to expand...

It was RIGHT after lights out. Like seconds after. Then I got the hell out of there!

Tim1987 said:

Is that yellow patch directly under the bulb??
Whats your ppm?
6.4 is probably pushing it just a touch too.

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I’m growing in soil. You think it’s too high?

Yes the yellow patch is closest to the light.

ppm was about 744 last feed. That was high actually, I’ve been spoon feedin ‘em.

ClassicT said:

I’m growing in soil. You think it’s too high?

Yes the yellow patch is closest to the light.

ppm was about 744 last feed. That was high actually, I’ve been spoon feedin ‘em.

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Nah you should be fine in the soil.
Id say your light did do that. Giving it more ppm would have amplified it too.
Cutting ppm was a good idea!
If you're just under 6.5, you should be sweet.
Have you been watering with good runoff?

Tim1987 said:

Nah you should be fine in the soil.
Id say your light did do that. Giving it more ppm would have amplified it too.
Cutting ppm was a good idea!
If you're just under 6.5, you should be sweet.
Have you been watering with good runoff?

Click to expand...

Yeah, I think you’re right, the heavier feed did seem to set it off. Damnit!

I was watering more sparingly in veg, trying to reduce intermodal stretching by letting them run a bit dry. Maybe 5-10% runoff in veg.

I’ve been soaking em more in flower, trying to get the buds to really expand. Getting more like 20% runoff. My last feed was very very light, so this time I went for it. And soaked em down good.

Too many changes all at once.

Man, talking this through with y’all has been SO HELPFUL. I totally get what happened now. I’m pissed I set the girls back a bit, but hell, I’m brand f*cking new at this.

Thank you!!

ClassicT said:

Yeah, I think you’re right, the heavier feed did seem to set it off. Damnit!

I was watering more sparingly in veg, trying to reduce intermodal stretching by letting them run a bit dry. Maybe 5-10% runoff in veg.

I’ve been soaking em more in flower, trying to get the buds to really expand. Getting more like 20% runoff. My last feed was very very light, so this time I went for it. And soaked em down good.

Too many changes all at once.

Man, talking this through with y’all has been SO HELPFUL. I totally get what happened now. I’m pissed I set the girls back a bit, but hell, I’m brand f*cking new at this.

Thank you!!

Click to expand...

No worries mate.
Think you'll be sweet anyways
Happy growing bro.