I have for seedlings that are 3.5 weeks old. I am using a 450 watt viparspectra LED lamp. On the third week I change the light setting to 18 / 6 with the viparspectra light setting on 100% veg and 50% bloom. The temperature in my grow room ranges from 75 to 80 degrees in the humidity level ranges from 47 to 55 percent and I'm pretty positive I have good airflow. I noticed the cupping two days after I switch from 16/8 to 18 / 6 on the light hours. So I'm thinking it is like stress I had to plant about 19 or 20 in from the light and on the instructions it recommends it be 32 to 36 inches from the light so I dropped it down to 30 inches the cupping seem to calm down but I've noticed the cupping has started again a day later after about nine hours of the light being on. So I want to scale the hours back to 16/8. I am using foxfarm ocean forest soil have not had any nutrients yet do not need to. Does anyone have any other ideas this is the only one I can think of so far.
Yeah they look a little stressed mate but theyre fine. 30 inches sounds about right for that light. Hit google for "vpd cannabis chart" have a look at that and read a couple articles. It explains how temps and rh work together. Read it yourself though itll give you a better understanding than i can explain lol.
I just checked that website out. It makes sense, but im not sure if thats the issue, mabey but idk. The cupping gets worse after 8 or 9 hours of the light being on, .. on that website it says if your humidity is 50% your room temps need to be 65, ..75 is the lowest i can go, and i thought that is ideal temperatures....i still think light stress
It's not just about the general room temperature Place your hand just above the plants for a while, how does it feel?
Well, then you already know what is the most likely cause of the problem, go back a step. It may also be a humidity problem.
Yea i have an idea, but we shall see...and you do have me raising an eye brow about the humidity...i have a humidifier in the grow room. If i dont have it in the room humidity quickly drops to 30% ....with it on the room is at 50% humidity
I have no idea what my humidity is in or out (I have my plants outside during the day) but I spray may plants with water usually several times a day, if it is not very humid outside.
I wouldn’t be too concerned myself or actually change anything That You are currently doing if I were you.. it may just be a slight overwatering or humidity issues at play here not light stress or PH issues. These ladies look healthy and beautiful and will 100% resolve themselves, just never allow the Humidity to go over 70 or under 30RH for too long if possible; to avoid any pathogens, mould or transpiration complications. Sent from my iPhone using Tapatalk