How hot is "too hot"?

I've got an A/C unit and I can regulate temps down to 62f if I'd like, so I'm looking for a good "zone" that I don't have to worry about. I've got 300w of CFLs and 150w HPS going. Is 86-88f fine?

Jhow said:

I've got an A/C unit and I can regulate temps down to 62f if I'd like, so I'm looking for a good "zone" that I don't have to worry about. I've got 300w of CFLs and 150w HPS going. Is 86-88f fine?

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86-88f Is too hot. Ideal temps are 72-75f lights on.

My temp gauge displays the highest and lowest of the last 24HRS and I will glance at it to make sure it's always in the range of 65-80.

They say you should treat it like a human, what Temps would you like and to what degree?

Don't forget about the humidity possibly adding to it. I have virtually none in the cab so I'm fine with Temps running a little higher

It's 23% humidity and if I put my hand over the plant you can't even feel heat. There is a huge A/C unit pumping 70 degree cold A/C into the bottom of the tent. The temp reader is directly under the HPS (maybe 6-7") which is why I think it's in the 80's? I've got one fan blowing on the CFL's, and a smaller one blowing on the HPS from about 3' away. I can touch the CFL's and not feel any heat.

Would it be worth it to get two more readers, one for the bottom of the tent and one for higher up top to see what type of zones I've really got going?

you'll be fine with those temps

I have one of those electronic thermometers like MrPuffins too that record the high/low for temp and RH. Left my RH control too low last night and it was down to 61F in there this morning.

75 is about the sweet spot for growing without CO2. If you have CO2 then 85 will really grow the plants fast if they have lots of light and food too. I've been manually dosing my plants with gas from a welding tank the last 5 or 6 days while in early flowering and both me and the plants are loving it! I'd probably be seeing signs of nute burn without the CO2 the way I've been feeding them but with it and 2 - 400W hps bulbs lighting them up they are putting those nutes to good use.

I keep my thermometers off to the side so they aren't affected by the radiant heat from the lights and there's an oscillating fan blowing all the air around so temps are fairly even from the floor to the ceiling. Just got one of those digital temp guns yesterday so I can get the temp of the leaves right under the light. Leaf temp was 101F last night when the room temp got up to 92 and I could see some leaves curling a bit so I got to watch it closer. CO2 controller is at the top of my wish list now but blew all my dough on other grow goodies already.

Thanks all. I've also got one of those Acurite's that show high and low (temp and humidity). Humidity runs 17-32%, and temp runs 77-88 (currently 84). I think it might be where I'm placing my temp reader? I'll move it around over the next day or two and see what it shows.

Shade the thermometer under the foliage and take another reading. 85f isn't too bad if you've got a little humidity, but i don't see 20%rh/85f working out under an hps though

Ive had canopy temps up and over 45c (113F) in inside grows in western Sydney in an apartment. HID grow. Summer in western Sydney can be brutal.

Didnt bother them at all but they did drink allot and were germed in those temps

Jhow said:

It's 23% humidity and if I put my hand over the plant you can't even feel heat. There is a huge A/C unit pumping 70 degree cold A/C into the bottom of the tent. The temp reader is directly under the HPS (maybe 6-7") which is why I think it's in the 80's? I've got one fan blowing on the CFL's, and a smaller one blowing on the HPS from about 3' away. I can touch the CFL's and not feel any heat.

Would it be worth it to get two more readers, one for the bottom of the tent and one for higher up top to see what type of zones I've really got going?

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Just a question....... As heat rises and cold air drops, even though it sonds like no problem so far, if you DO encounter a temp prob, switching your cold inlet to the top could help, but if your A/C unit is only pumping in 70 degree air, I'd look into that first.I've run a 2'x2' closet grow with plenty of CFL's, and only had a fan blowing up from below, with temps as high as 80. Always done well with good beans, but cheap/ bad beans always give less quantity and softer buds.
Couple of the 'Old timers might remember the East Coast Sour D' I was real proud of, got over 4 3/4 oz. from it with CFL's. Back when I used to hang out here, that's all used. Nw I'm playing around with outdoor a little

Good points, Bakatare - my thoughts were the same as yours. I've got a filter at the top sucking the hot air out of the tent, at the same time I've got an A/C unit blowing cold air in. Outside the tent it swings from 66 (overnight) to 74 (when I'm here all day). It might not sound like it, but putting your hand inside the tent at the intake vent, the air is REALLY COLD at only 70 degrees. And it's moving at a pretty fast clip. So, you've got this nice cold air pushing the hot stale air upwards and being sucked out the tent. The pots are elevated on bricks to allow for air circulation all along the bottom of the tent.

I've been watching it closely and it's been 84 since yesterday now that I've set a hold at 70 on the A/C. It really doesn't feel hot at all inside.