So I just got my 2x4x6 grow tent set up. It’s in a basement room with no direct heat source in that. I just hung an HLG 260W XL. Much to my surprise, this thing really doesn’t give off any heat at all (at least not with the potentiometer at about 75% – not ready turn it up just yet on these seedlings). So the tent is running about 65-68 degrees pretty consistently. For a litany of reasons, it would be difficult for me to run a space heater. Anyone see any issues with the temps being under 70 for the duration of the grow? If so, is there a decent supplemental light that I might hang to generate some additional heat?
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I run my Winter grows between 64 and 72 with no problems.
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Those temps are fine. I’ve grown in my basement in those temps. 
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They might grow slower than they otherwise would in warmer temperatures, and you might need to watch for mold near the end if they get dense. Humidity won’t need to be as high if it’s cooler, so you probably want to have a look at a VPD chart. Once you have some plants in there, it may warm up some, but the humidity will definitely increase. You might be able to play with airflow to warm it up some, too. For example, using a passive intake instead of a fan, slowing your exhaust, etc. You could pop a couple CFLs in there for some heat, or if it comes to that, even a small heat lamp if they get too chilly. The good part is, it should be pretty consistent in the basement. Good luck! 
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I know to get those vibrant colors you see sometimes you gotta be around 50 so I’d say anywhere above there.
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Hey thanks for chiming in!
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So i really want to be in that green zone throughout the grow? I was kind of thinking 40 RH during flowering would be a good target, but looks like that might be way too dry for the temps I’ll likely be dealing with. Hmm…
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If they’re still really small, you can put them under a high humidity dome in a seedling tray, and use a seedling mat. I mention that because a seedling wants high relative humidity, which is easier to achieve with warm air.
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You can really do whatever you like, as it’s your grow. Tho most growers try to use that as a reference
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Here is another VPD chart. I like it because it breaks it down by growth stage without getting to crazy like some charts I have seen
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At night my tent has gone to the low 50s but It usually is at 59-63 at night and 72-79 daytime and no it has allowed me to cultivate some of my best buds ever bringing out the purples and ensuring nice dense buds. Found way more problems and lower quality buds in heat the cool just seems to help unless your getting below 50. I don’t use a heater or anything outside us high 20s at night and have had no issues just blessings like this cut down yesterday
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