Led grow room temperature

Hi,

so today I read (here and 2 other sites) that room temp shoud be 85f/29C.

Is that true ?

So for those of you running a small grow ( 300W max ), do you need a heater to reach this temp ?

Thanks and have a nice day !

85F is a little on the hot side, imho. I run 78-82 with a temperature controller....when it's cold, the lights warm the little cabinet I have, then the fan kicks on at 82F, turns off at 78. A 300W heat source should heat the small grow area no problem, unless it's open space in a large room/tent/space.

thanks @mc130p ! yes small space.

Everyones situation/strain is different. There is no set temperature. Some plants like lower temps, some like higher. Humidity and airflow can change the "ideal" temp as well.

That said, after about 2 years with COB growing, 85 is way high. I find that once the temp hits 80, its cause for concern (in flower, Veg is fine). Anything over 82-83 and the plants slow down and get sad. Some people say they have issues with low temp growth. Ive found that anything between 70-80 is just fine for COB. I actually had better results with hotter temps under HPS than I did under COB.

thanks @doz !

well I asked because I found it high too.

i have more issues with low temp growth.

when my air above my canopy is 85, ir temp gun on canopy says 75-77 and im all

Hi @CobKits, it's your post I read !

You reach these temps witout heating ? how many watts ?

thanks !

drgroove said:

Hi @CobKits, it's your post I read !

You reach these temps witout heating ? how many watts ?

thanks !

Click to expand...

its in my basement and its 100 degrees outside,

but i also keep my humidity at 60-70 for most of flower (ramping down both temp and humidity in the end.

i see fastest growth at 85F air temp, 60-70% humidity and 500-1000 ppm or so CO2

CobKits said:

100 degrees outside

Click to expand...

ok

thanks @ganjamystic !

I always feel the problem is more with the temperature below the canopy. It tends to get way too cold there.

Hi @wietefras,

interesting ! any input on temp diff between "top" of canopy and "bottom" of canopy ?

And you have a nice cool root zone ?

Another consideration to raise temps a bit would be to circulate air near the lamps down into the canopy. The heat typically moves up and out via an exhaust fan so there may be no reason to add additional heat when it can easily be cycled in the grow space. If the tent is 90F at the top and 70F below the canopy that can be used to advantage.

yup and many active cooling solutions do just that

Hi @Rahz, good point.

what I'm wondering is how we can have such a difference in temps with all that air circulation ?
(with circluation like : exchange grow room air 3-5 times per minute).

When the air leaves the tent it's warm and tends to stay up high. It move through the doorway up high while cool air is drawn into the room at the floor. It radiates through the walls and ceiling at what rate depending on the insulation rating. Even if the door is closed it will still seep through cracks in the door, walls, ceiling. Every situation will be different so with similar ambient in a building one person could have a room that gets too warm with not much wattage and another person could have a room that's cooler with higher wattage.

thanks @Rahz, never thought of this !

Yeah exactly, you have to put some effort in getting the heat down to the plants. As opposed to growing under HPS.

What I do hate though is when blowing the warm air down onto the plants, you get these dried out leaves in the tops. So I stopped doing that,

I tried circulating the air from the top and through a pipe back into the bottom, but I had some issues getting the temperature above 24C (75F) with that. Even with the exhaust fan at minimum (which gave very high humidity). Guess the plants started transpiring a lot more all over and in doing so cooled all the heat away. Been wanting to try that again, but it's something you can only do with plants in the room and I don't want to mess too much with flowering plants either.

intersting again !