• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

How low should temp be to harm a plant?

Helmut79

Helmut79

Well-Known Member
I had to move my plants out from my house and I'm about to set up the new place for them, but this place has some temp issues I will need to fix within next few days.

I have 8 big plants which are vegging + 28 seedlings which are about to start their second true pair of leaves.

Big plants have 1000W HPS on them and seedlings have 8x 23W CFL on them. I figured they would be okay as long as the lights are on, but what happens if they have to be in 5-10C (40-50F) at night time for 6 hours?

Are they going to survive or might that low temps put my plants & seedlings at risk?

Temp issue will be fixed within 3 days though..
 
chairroller

chairroller

Active Member
With normal levels of CO2, in a well vented space, 90 degrees would seem to be the absolute max, while 85 may be closer to optimum, even with a great deal of light available. Do not let the room temperature get over 35 C (95 F) as this hurts growth. Optimal temperature is 27-30 C (80-86 F) if you have strong light with no CO2 enrichment. Less than 21 C (70 F) is too cold for good growth.
Low temperatures at night are OK down to about 60 degrees outdoors, then start to effect the growth in a big way. Mid 50s will cause mild shock and 40s will kill your plants with repeated exposure. Keep your plants warm, especially the roots. Elevate pots if you think the ground is sucking the heat out of the roots. This is an issue if you have a slab or other type of cold floor.
From here: http://weedfarmer.com/growing_guide/temperature.php

 
Bugeye

Bugeye

Well-Known Member
Just leave your 1000W on the whole time since you aren't flowering. I've had plants in the 40's many times and it does not kill them. But if they are not used to temp extremes like you get with outdoor grows, it could shock them and set them back a bit. The 30s are where it really gets touch and go.
 
topfuel29

topfuel29

Well-Known Member
Cannabis can take some cold temps. It's the duration of cold that kills them.
I've had plants as cold as 19F, but for only 4-5 hours.
They might wilt a little bit. Don't worry they'll bounce back.
When your soil starts getting cold you will start having problems
Nutrient lock out. starting @ 60F the colder the soil the more problems you'll have IME
6 hours that's nothing they'll handle that no problem.
Your soil won't have a chance to get cold in that amount of time before the lights come back on.

Good Luck on Your Grow.
 
You must log in or register to reply here.
Top