Low temperatures - Growing in a backyard shed.

Discussion in 'Indoor Growing' started by Metacanna, Mar 16, 2017.


    Metacanna Well-Known Member

    Hey all,

    I'm struggling to keep my plants happy. My plants have been healthy and vegging for 3 weeks at constant 75F / 24C under 40W CFL, then I had to move them to my backyard shed where I installed a steel cabinet which I'm using as tent. Right after the change, the plants immediatly started to look droppy, 3 days now and no signs of recovery, stopped growing. Temperatures fluctuate between 59F / 15C and 70F / 21C, most of time temps stay in the 62F/64F range.
    I turn on the lights during the night and turn off during the warmer part of the day, respecting the 18h cycle. This way temperatures never drop too much.

    At first I thought they were receiving too much light as the lights could be too close, after a few adjustments I didn't see any recovery signs. The possibility of overwater and underwater is excluded, I have done enough grows to know how to properly water my plants.

    This led me to think that the problem is related to temperatures only. Yeah, I know MJ grows best in the 70s up to 80, but I was not expecting this drastic reaction.
    Will my plants get used to low temperatures and recover? They will grow slower at lower temps, but they are not supposed to die with this temps!
    Side by side with this 2 plants I have an auto strain doing great, she had been exposed to lower temps since germination so she might got used to.

    It would be really frustrating if I had to use and oil heater inside the space. At first I pay premium for high efficient lights that produce more light output than heat, and then I'm going to pay for a heater plus the electrical bill? Nah...

    Anyone experienced growing at this lower temps?


    SouthCross Well-Known Member

    I have a 7 week old bubblegum male that went from 76f/68 in the grow room. To 42f at night with a high of 70 outside. He's been growing in low 40's for around 5 days. We even had a frost. It burnt the yard grass but not him. Not a spot on any leaf. 2 gallon smart pot. He's by a fence so I suspect that's how he missed the frost.

    I'd figure he'd be dead or slumped over. Something. Right now it's 53f, 92% humidity.

    The basturd just won't die and he's beautiful. If I did the same temps in the cabinets. I'd kill/damage the whole lot.
    Last edited: Mar 16, 2017
    harris hawk likes this.
    harris hawk

    harris hawk Well-Known Member

    marijuana is a hard plant to Kill - things will be OK
    Moflow likes this.

    thumper60 Well-Known Member

    if in veg run the light 24-7
    Urbz and NrthrnMichigan like this.

    dabbindylan Well-Known Member

    Water less yo
    MMJ Dreaming 99 likes this.
    MMJ Dreaming 99

    MMJ Dreaming 99 Well-Known Member


    Metacanna Well-Known Member

    Hey. Thanks all.

    If the point of vegging 24h is to get constant warmer temps I guess it would be wiser to get an oil radiator, it's more efficient producing heat and I wouldn't risk stressing my plants due light schedule.
    Today temps have raised to 70F-72F but plants didn't show any signs of recovery. 4 days now with plants completely stunted. Now I'm curious to see if they will come back to life.
    MMJ Dreaming 99

    MMJ Dreaming 99 Well-Known Member

    Dude go to the store and look for a small heater with a thermostat. About $20 to $25 US. You set it for 70 deg F or whatever. Problem solved.
    visajoe1 likes this.

    Xcoregamerskillz Well-Known Member

    I was running my plants in my pantry, coldest part of my house, your growth will slow, but should be OK so long as the roots don't freeze
    Metacanna likes this.

    Metacanna Well-Known Member

    One week has passed and new growth is now slowly developing, however all old growth is slowly yellowing and dying from bottom to top. It's very unlikely it is nitrogen deficiency as I'm feeding and using rich soil. In all plants that suffered the shock same is happening.
    Temps have been fluctuating from 55F up to 70F.
    It must be that the temperature shock caused some sort of damage on the roots and/or in the tissues, maybe the new growth will handle the situation a bit better. I expected to start flowering this week, seems have to wait till full recovery..

    brewbeer Well-Known Member

    If your plants are sitting on a cold concrete floor, that could translate to cold roots and slow growth.
    Jaybodankly likes this.

    nevergoodenuf Well-Known Member

    I have used a dehumidifier for extra heat at night before.

    Metacanna Well-Known Member

    My plants are staying inside a steel cabinet, if I knew I would have this low temps I would have built a wood cabinet instead for better thermal isolation.

    I have some new clones ready to go in, if same happens it means the shock is too significant for plants to handle, no matter strain.

    The solution will be pretty simple. I will do autos during winter and photo during summer. Having the lights 24h on allows to keep the temps warm and constant during all winter. In summer when temps don't drop that much, here goes min 65F I will be able to have photo plants.

    Metacanna Well-Known Member

    To conclude this topic, I wanted to share what really happened.
    I realised that the cause for my plants to stop growing, yellowing and curving down was mainly related to too much light. I'm using COBs for the first time, this lights are more intense than an HPS and I had them 10" from my plants, this was bad idea. As I increased the distance the plants started to show signs of new growth and are now slowly recovering.
    So with such an high light intensity plus cold temperatures the plants simply couldn't do the photosynthesis efficiently, thus stressing and damaging the plants. With lots of light the plants need to transpire and transport water and nutrients through the stems at an higher rate, however this transfer is affected by low temps. So, that's why. I guess.

    visajoe1 Well-Known Member

    yikes! 10" is close if you're running the standard 50w. combined with the lower temps, I can see why she took a break

    GvegasGrowa Well-Known Member

    So I run a 600w in my garage. 3x3 tent. In new england. I use a little space heater with a temp controller. Does the job, but the space heater will use 500 to 1500w depending on the setting (or how cold the weather will be). The electric bill is like 75$ more with the space heater.

    Moflow Well-Known Member


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