Heat Stress, But Maybe Humidity Or Ventillation Issue Or Overwatering??

Leaves exhibited "taco" leaves which is a sign of heat stress that we got when we went to 1000 watts (metal halide). We found when we reduced tent heat from 80 to 75 it helped a lot, BUT leaves are drooping, stems are high so we figured over watering, but water level is fine - 1/2" below bottom of rockwool. We have an oscillating fan about 5 feet from plants blowing over em- could this be causing the leaves to be dry? Ventilation is pretty minimal- only two 12"-long (4" high) rectangular flaps at bottom of tent are open. Just not sure, they are at very end of week 2, chiller water temp 70, RH 70, day temp sometimes 80 but now getting it down to mid 70's (night 70 air temp).

Just not sure what is off in the climate..>???

Image 3416 (last picture i think) is 90 minutes after lights on (they tend to perk up)
 
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Jack og

JackOG
Staff member
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Well a lot is going on here:
Lights, what height is it over the plants?
Nutes, what is it getting?
Temps are higher then what it should be.
I’d say give her a few days to recover post changes you’ve made so far.
Throw a bit of silica foliar spray. Helps it recover and build stronger stems and stalks.
 
Well a lot is going on here:
Lights, what height is it over the plants?
Nutes, what is it getting?
Temps are higher then what it should be.
I’d say give her a few days to recover post changes you’ve made so far.
Throw a bit of silica foliar spray. Helps it recover and build stronger stems and stalks.
Hi Jack, thx for taking an interest. I'll check out silica foliar spray tomorr at hydro store. We've steadily been moving air cooled light (8" XXXL) down from 40" from top of leaves and now we're at 27". We only move when plants stop showing signs of taco leaves. But even today earlier air temp hit 82 and then they show the sign. Now we're keeping room at 75 during light on.

My concern is more with the droopyness and also the dryness of the leaves. Concerning the latter, I've been keeping RH high (70) to try to combat dry leaves and also opened another vent at bottom of tent and reduced strength of oscillating fan back to minimum setting.

Also, using UC nutes, week 2 ppm's were 240 and dropped to 225 while pH stayed steady at 6.2. week 3 (today) feeding shot it up to 425 ppm! BIG JUMP, and pH of 6.1. I'll monitor tomorr. to see how the plants respond but we followed the feeding (recirculating hydro chart) to the exact amount- 2ml/gal UC roots, 1.5ml/gal Coco Cal and 2ml/gal of Veg A and 2ml/gal of Veg B
 

Jack og

JackOG
Staff member
2,113
263
Hi Jack, thx for taking an interest. I'll check out silica foliar spray tomorr at hydro store. We've steadily been moving air cooled light (8" XXXL) down from 40" from top of leaves and now we're at 27". We only move when plants stop showing signs of taco leaves. But even today earlier air temp hit 82 and then they show the sign. Now we're keeping room at 75 during light on.

My concern is more with the droopyness and also the dryness of the leaves. Concerning the latter, I've been keeping RH high (70) to try to combat dry leaves and also opened another vent at bottom of tent and reduced strength of oscillating fan back to minimum setting.

Also, using UC nutes, we went from 225ppm's today at end of week 2 to 425 ppm's tonight when we did week 3 feed- BIG JUMP in ppm's. I'll monitor tomorr. to see how the plants respond but we followed the feeding (recirculating hydro chart) to the exact amount.
Yea it’s just adjusted to the new regiment, always do incremental changes , nute , go up 100ppm a time till you reach the max
Lights with the xl hoods do put out a lot of heat, so maybe adjust the fan an outgo, in line fan pulling through at out the tent. Remove the glass cover to to allow it to pull air across the bulb and run it cooler
 
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It looks like they are getting a little too much of something...maybe Phosphorus. To me, it looks like it is on the edge of being over-fed/hot nutes. I'd cut back on the feedings a little, although Nitrogen is always good to have available and doesn't seem to be an issue here. I don't think the heat is an issue either, although the heat might make the symptoms more notable. When plants get the deeper furrows on their leaf surface, the 1st thing I consider is an excess of something. Deficiencies might look somewhat similar, but don't seem to cause to deeper leaf rows, at least in my opinion. It can cause burning/dryness as well.
 
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I think the lights are too strong and need to be raised. Lower only a little at a time as the plant gets used to the higher wattage.

I disagree with adding any new products during plant stress. Always look to the environment first.

Do one thing at a time and a little at a time as a process of elimination when something looks wrong is the best advice I know.
 
So didn't know the UC feeding schedule assumes you're doing a nute changeout every week (yeah freaking right!) So we're gonna drop the ppm's down to 350 (only been 425 for a day). I don't know if the humidity is too high or low tbh. I'm keeping the RH 5% higher than UC chart so week 3 of Veg I have RH at 65. My thought is it's too dry w/ the fan blowin.

Jack- We got silica blast but turns out it's not a foliar spray. I was told by guy at hydrofarm that silica is good to prevent heat stress, but you can't really foliar spray silica cuz the leaves won't absorb it?? Should I just add the sucker to the epicenter like guy said or is there a diff. product that can (and should) be sprayed?
 

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