its when your temperature is too high or cold, and is not in ideal conditions for growing cannabis. there is a range typically 75 to 86 degrees. any higher you could burn the plants, and lower slows growth, and adds stress
I just went through it in my veg room. If your room is to hot for to long you can get serious potassium,and phophorus lockout.And a few trace elements as well I believe. Your plants will start dying pretty quickly once this is in full effect.I almost lost my next flowering cycle plants "not paying attention to the rooms temp for a couple weeks".I never had an issue before. At this point I'll have to extend my next flower window for recovery time as they are still bouncing back,and I'm 2 weeks form next harvest.O well these things happen.