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Advice about wattage of LED light

I see that you are talking about your rig yes
I don't have heat issues cause is cold outside, its like 41F or 5°C
Atm is like that :
- air temperature is 73F or 23° C
- canopy temperature is 79F or 26°C
With boot lights on and the led pannel with booth switches on
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Member of the Month: May 2009, Oct 2010, Sept 2017
Not to hot but I don’t like running at 81-82

Any particular reason? Cannabis appears to be able to process more light-energy at higher temperatures (up to a point, of course, but I'd guess that point to be a few degrees warmer than 82°F). Although, come to think of it, that probably doesn't take into account strains that evolved in (or were bred for) a lower temperature environment.

And ambient CO₂ levels are higher than they've been for at least 800,000 years, so the actual non-supplemented upper temperature limit might actually be a tiny bit (a degree, maybe) higher than what we've traditionally been led to believe.

Do you see excessive stretching or the like at slightly higher temperatures than 81-82°F?

I'm not saying that you're wrong to aim for the temperature that you do. And everyone runs different levels of light (per a given area), different strains, et cetera - so there's going to be some variance in "best temperatures," anyway. Mainly... I am just curious, and looking to add to my knowledge (and/or correct what I already have ;) ).


Well-Known Member
You just stated a lot of good factors tourturedsoul In fact it seems you may know quite a bit more than me about growing. I think I’m just used to running these temps and conditions because I have no air conditioning in the summer and I’m constantly dealing with heat issues. Now that I know what works for me I just stick to it for now. That would be why I use only one or the other on the meizhi 900 (veg or bloom) because full spectrum is just to hot for my liking. For flower I keep just bloom on wich runs just a c hair lower than half power with a supplementary led


Member of the Month: May 2009, Oct 2010, Sept 2017
You just stated a lot of good factors tourturedsoul In fact it seems you may know quite a bit more than me about growing.

Maybe. <SHRUGS> But maybe not, lol. Please do not assume that I am an expert (at anything) just because I "talk" a lot and have a few posts. I would never knowingly post incorrect information, of course, but... I've got as much chance being wrong as the next person. It wasn't until relatively recently that a couple members finally managed to get me to stop using the (incorrect) term "phototropic" when I meant photoperiodic, as a way to refer to "cannabis plants that depend on a certain number of hours of uninterrupted darkness per day in order to flower, instead of being auto-flowering strains." I started calling "normal" (lol) cannabis seeds "phototropic" years ago, and used it ever since. Just never really thought about it, you know?

At the end of the day, whatever works best for you is obviously... the best thing for you to do. I'm kind of an advocate for changing one thing at a time with one or a few plant(s) in order to see whether there is an improvement, detriment, or no change - whilst keeping the rest of the plants the same as before, as a control group. But in regards to grow room temperatures, that seems like it'd be pretty difficult. The space is either warm or it isn't, lol (at least with decent air circulation), so it's pretty much an "all or none" kind of thing. That not only means it's difficult to truly judge the difference a (reasonable) change in temperature - by itself - makes, it also means that if such a thing turns out to have been a Bad Idea, it hurts the entire crop instead of only one or two plants.

I also have heat issues here, BtW. Last year, I was seeing mid-high 90s outside of the grow room, so... And I was growing in soil instead of DWC, so the plants didn't have that survival aid (being able to transpire 10 or more gallons of water per day, each, in order to self-cool, lol). I was so chuffed when our local unreasonable heat wave finally broke - well into Autumn :rolleyes: . I could finally do a decent grow, yeah? And then, a month later, my lights-off temperature was in the 40s. <SIGH> I'd like to have both the electrical capacity and the money to run a dual-flowering setup, alternating. That way, I could exhaust the heat from one into the other (dark at that time) grow space. But I'm operating on a shoestring budget... without the shoestring.
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