Some help with temperature

Hi all,

I am certain this has been asked, and answered, many times before. The problem is, I am having tremendous difficulty searching for it because it is such a generic term, there's too many irrelevant 15+ page threads to wade through!

Can someone point me to a couple of good threads that explain optimal temperatures for growing our favorite plant? Flowering daytime temperature, flowering nighttime temperature, vegging temperature, etc. What is the ideal temperatures we are trying to hit to get the best results?

Thank you!

Too tired to get you a link but I know for a fact that the ideal range is between 70-80 degrees. Anything in that range and your golden. Once you get into the 90s the plants slow down in growth and if you get into the upper 90's they stop growing. Probably get all stressed out from all the perspiration and die from salt build up. Keep it under 90, even 89 is not too bad. 90 is danger zone, good luck

ive read that between 70-85 is optimal.

Word thank you both.

70-80 only go higher if your using CO2 cuz if you dont and you get over 85 your plant will go into survival mode and not grow that good.

What about minimum temps? I know that it is important to keep temps BELOW 80-85F, but is there a minimum that you need to keep your cabinet ABOVE?

daytime temps under 60 slow growth and ripening and during night 55. if i helped feel free to send some rep my way.good luck

Ok, so I gotta figure out a way to keep things above that temp...

Does anyone know how much heat different HID lights give off? Is there some kind of metric that will measure how many degrees above ambient, per cubic foot, per hour, or something?

Like for a 150w MH in a 6 cubic foot enclosed space, how many degrees above ambient will it get, and will it get hotter every hour? And how does air cooling play into that, for example if I have an intake vent in the bottom of that space and an exhaust fan at the top, and am expelling the air x times per minute, how much will that cool it down? Do these kinds of data exist?

Ok, I have done a little more digging, and I think the measurement I am looking for is BTU. Does anyone have BTU numbers for different HID lamps?

Well, I wasn't able to find the BTUs for HID lights, I guess that makes sense since people are concerned with their lighting ability but not their heating ability.

So I have re-oriented by outdoor box to get air to flow from flowering chamber (where there are two all-in-one ballast/reflector/bulb fixtures) out into the mom chamber (150w MH) and then into the cloning/drying chamber. Also the cloning/drying chamber is directly above the flowering chamber. That should make maximum use of the heat to keep the box warm.

There will be a centrifugal fan in the cloning/drying chamber to exhaust the air from the box into an odor killer. I just need to adjust the fan speed so that the three chambers are all within optimal temps, 65-85F.

Of course, all that only applies when the flowering lights are on. To keep things warm while the lights are off, i'm going to add a heating element to the air intake. I got the idea off Al B. Fuct's bud dryer, the element is off a small ceramic space heater. Still haven't figured out how to control the element using a thermostat (the element itself is either on or off).

all sounds pretty interesting mate,have you got any pics of your grow?

simple grower said:

all sounds pretty interesting mate,have you got any pics of your grow?

Click to expand...

I didn't take pics of my last grow, it was a few years ago.

Current grow is still in the design stages, so no pics yet. I have over a dozen revisions of the cabinet drawings scattered on my desk though lol!

this subject has been beaten like a red headed stepchild for years. one book will say this, while another will say that, and still another will say something totally different. marijuana will grow in the spring, right out of a snowbank, and it will grow in the dead of summer 115 degree heat in the california valley without issues.


in my grow room indoors, my daytime temps generally range between 80 and 90, and nightime temps between 50 and 65, and i have never had any issues with potency, dormacy,damage,ect.

so in my own 30 year+ experience, id tell you keep your daytime temps between 70 and 90 in the veg stage, 70 to 80 in flowering. night time temps can vary quite a bit as long as you dont let them get to low.

is it actualy better to have a higher temperature if your using plenty of co2, or should you keep it at at the same temperatur?

you should grow some plants and figure it out yourself, MR. NEEDY, you have at least 15 posts of good advice