leaves curling... would this be heat stress?

[BBD32]

This one has been vegging for a month and a half. Its under a 1000w metal halide. The soil is m3, 5gal pots, pH 6.5, the strain is super lemon haze. Temp is 75 with lights on and 67 is the coldest it gets when the lights are off. No additional nutrients have been given.

Could this possibly be heat stress? There was 2 days that the heat hot over 90, I have since fixed the issue. The leaves are curling at the top of the plant and getting brittle. Any ideas?

 

[OrganicMan]

Hello mate

I think this could well be heat stress. The plant will try & conserve as much water as possible by reducing the surface area of the leaves thus less transpiration. What's the airflow like in your room? What's the humidity? & when did you last water/feed? What's the ph? Just trying to get a all round idea

 

[BBD32]

Very sorry for the lack of info... I have a 12" oscillating fan on them constantly, an 8" hurricane intake 6" exhaust with 25" carbon filter. Humidity ranges from 48% when lights are on down to 31% with lights off. Watered 2 days prior to the photos listed above. PH when watering is 6.5 not sure on soil since my ph probe is terrible. I haven't gave any nutrients as the Michigan made mix I used for soil claims to be a start to finish soil. However I just noticed a few deficiencies. The deficiencies are posted below.

 

[BBD32]

I'm guessing heat stress because the that plant is 3"-4" taller then the others and is the only one affected.

 

[NuttyProfessor]

yes heat , measure the heat at the canopy , i take it this soil has built in nutes as you said start to finish soil ?, wouldnt recommend it , when you water you feed and its hard to flush as you still feed , maybe the ph is out of whack now a touch , the white marks look light light bleaching to me

 

[BBD32]

They look white in the pics but the spots are actually more orange-yellow. As for the heat at the canopy, 78° is the highest the temp gets. I'm going to check the pH of my runoff next watering, what is acceptable for runoff pH?

 

[NuttyProfessor]

6.3-6.8 for soil.

 

[NuttyProfessor]

i am no expert , i have a ph pen i never use , i make my own compost teas up and the soil seems to buffer its self , i dont really get any issues thankfully ,

 

[NuttyProfessor]

found this , remember reading it once . as i say i threw my ph pen on top of my kitchen cupboards and never used it again , keep the soil good , you should do read reviews on the strain you grow, some dont like it as hot as others

here is that link Measure pH directly in soil or from run-off water?