low temps

Hi everyone,
Just doing some speculation here, and usually my problem is quite the opposite. I am doing my first indoor grow in this area, usually temps reach 80-90 Fahrenheit, sometimes nearing a 100 during summer days. So I never really had to deal with the issue of low temps.

I have never done an indoor grow here and the temps are dipping into 50s, maybe even mid 40s right now during night. It didn't even occur to me. During the day we are cruising at about 65-70 and with the lights running during daytime hours it's not a problem.

Only recently did I put a heater in the grow room. 2nd night now, and I'm able to keep them at about 65 degrees on average. I will also be raising the pots off the concrete slab by inserting wood boards underneath.

I understand that running a 1000watt hps during night time would help the temps, but light leakage is a concern during day time so I chose to run my light during day and have absolute dark at night.


My question is for any experienced growers out there. Have I significantly harmed my yield by letting the temps dip that low during night (dark period)? I am a week into flower now. Plants look healthy and happy with 0 deficiencies. I have corrected the problem. but my concern is how much damage I might have done by now.

if they're shocked it might take 2 weeks to resume growth but that's about it, assuming you're in late veg or early flower, early veg can hurt them for their lifetime, in late flower it barely affects them negatively. if you don't want to run a heater you could heat the in-air through an air-cooled reflector before it hits your garden

Ok good to know, temps started dipping definitely past veg time. Wouldn't the light have to be on for that suggestion? I'm thinking you mean something like a cool tube. However, my lights are off during night.

please explain what you mean by that. why would you want your plants in the cold?

I wouldn't let it get below 65 at any time, otherwise I'm pretty sure at the very least it would slow down growth.

Right on, take advantage of that cold air.
as long as you keep your soil warm 60's - 70's you'll be ok.
The soil gets cold the plant slows down, colder soil causes nutrient lock out.
It's pro-longed period of cold that kills the plant. I've had plants this winter as low as 19F the period was for a few hours I think It took the grow room to get that cold before the lights came back on.
But the roots take up water that's warm or warmer than the air temp, this protects the plant from the cold.
Usually in the 12/12 cycle the light cycle warms the soil enough to keep it pretty warm until lights on.
You just have to know these things, keep an eye on soil temp.


Colder temps you'll have more color full buds, more aromatic buds, Denser buds, bugs don't like the cold.
Don't forget these plant originally grew up on the side of a mountain. There tough plants.

Good Luck on Your Grow.

bondoman said:

I wouldn't let it get below 65 at any time, otherwise I'm pretty sure at the very least it would slow down growth.

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i agree they should be in the cold but not below 65

Very well, point taken. Thank you for all your responses.