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Sudden cupping & dying of upper leaves

2x2 Mars Hydro tent

2 MH led

Coco/perlite 65/35 in 3 gal fabric

Metered CO2 @ 1500ppm
Temp 36-37c
Humidity 70-80

FF trio nutes & Calmag

All fluids PH to 5.8-6.3

Bruce Banner auto x 8 weeks, flower x 3 wk

Monday: Curling & cupping upper leaves

Wednesday: Brown & cupping tips


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Just by looking at your notes

  1. You are at 37c might want to drop that 10-15 points and the same with humidity

They are to hot for sure is my thought…


They are on fire :fire:

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Thanks. I realize that the temps & humidity are elevated, but I gotta keep the tent sealed. 2 fans attached to roof provide only ventilation when CO2 is flowing.

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Can ya get an ac in the room with the tent? Also if you are exchanging air in a tent not sure but doubt Co2 is doing ya any good. I don’t run Co2 so I could be wrong on that. Temps are definitely the issue. Hot air also holds more moisture so just lowering the temps should help lower the rh also some…


Man …has rootbound been brought up??


How often are you watering/how much at a time and what is your e.c. ?

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Plants can get pretty big in 3 Gal with coco/ perlite mix I believe Dr. Bruce Bugbee uses somthing similar

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No room for AC unit. Feeding nutes day 1, H2O day 2, nothing day 3 ,repeat. EC ~1200 after nutes.
As of Thursday, I stopped CO2/turned on exhaust. Temp now 28c, RH 30. Flushed with ph H2o, EC 725.
Thanks for all the feedback.


Have you grown with coco/perlite before? It can greatly benefit from high frequency fertigation (multiple waterings per day with nutrients included). It also dries out really fast if your not watering, every third day when you don’t water your plant is going to have a very hard time keeping up with the temps. If possible I would try to even out your feeding schedule so they receive a consistent dose of nutrients and water everyday with less fluctuation.


I should hav mentioned this in my original post, this is my second grow & 1st in coco. My 1st grow was in soil, same setup. I used SOG (5 plants) with bag seed. Harvested 1.5 liters of loose, airy buds.


Doing much better. Thanks for all the input.