I have always went by a rule of thumb that 85* is about as hot as you want an indoor grow. I recently saw a discussion where an individual said that 85* only applies to the HID HPS/MH ect. lights. Their claim is that led puts out less IR than hps and causes less heatsoak into the plants. They said it was safe to run the led room temps up wards of 90-95*.
I am an led guy so that made me wonder and here is what i found. When my room is 85* the top of the plants are 79-80.6* and just below the canopy its slightly lower. Anyone out there smarter than me have any thought on this? My room has been known to hit 88* and I just about trip when it does. Should I not? Am i given an unspoken buffer because of the lower IR?
I find it strain dependent, some can take and even love high temperatures. Also humidity is vital, it drops as the temperature rises and if it goes too low your plants will probably suffer more from that than from the high temps. In my experience, led’s don’t tend to overheat the canopy to the same extent but they still can if you hang a powerful rig too close.
I don’t see a specific need to stress my plants beyond 84F…and its only that high since I slam them with 1300ppm of gas…non gassed I prefer to run 70-80F which over the years I have found to be the sweet spot…just my 2 cents.
I agree with Kraven,
I think to get any benefit (rapid growth) from running at high temp, everything including CO2 has to be at optimal levels. You’ll want to be dialed-in to the max, if you’re going to experiment up there in the high 80’s or 90’s.
My temps are affected by my location and atmosphere. With a 4 " line pumping HVAC and a booster fan pulling the HVAC into the room and a 6" carbon can exhaust, I’m lucky to keep my plants at 82-85*. That’s flowering at night, and dark during the heat of the day. I have to run my lights at partial power to keep the temps down. Lights are 36" above the plants, I have tried everything to be able to full power my flower, but my space just gets to warm I fear. If I turn everything on and seal the room up, it will settle at 87-89* full power everything.
I run a 2 ton mini spit I installed and maintain it myself…all for less than 1k…no need to be hot, there are solutions…grow room design is really important and right now you have a design flaw…not enough FAE to remove heat…unless your blowing 90+ degree air into the grow ???
My A/C in the Bunker runs at 74F year round…and at 100+ and over 80% humidity outside heat is a HUGE issue for me…well not once i got my room correctly designed to crank out dank.
OK I see, gotcha
I’ll use a laser thermometer to tests the temp of my closest colas to the lamp. If they are hitting 90F, I start raising the lamps up a bit. Unfortunately though, my experience is with HPS bulbs. I would think it’s a similar philosophy though.
Best of luck with the heat, my friend. I feel your pain.
Ac in is a crisp 70* ducted directly from the manifold on my homes ac unit. Maybe I need to up that line to a 6" as well, and up the exhaust to an 8". A mini split has long been a dream, but as of right now it’s not something I can afford. One day…
I also think that my environmental monitor my get heat soaked being black, and sitting at canopy height under the lights. Personally I like the feel in the room, but I’m not a plant… I would like it closer to my winter temps 67-73*. Lots of purple dank in the winter. I will cut back to just the Dom 2xxL for now, it’s 900 w (630 draw) dual spectrum, in a space that’s just shy of a real 3 x 4’. Room stays at 82* with it running full power. It’s enough light for the space, would just like to see if there would be much gain running both, and if the subsequent temps will ruin me in the end.
i’ve got the hot old poorly insulated house with weak A/C issue myself.
indoors using LED bulbs i’ve found leaf-burn can happen at 18" distance on a stressed plant, but healthier plants & a better RH% allow about 12" distance.
as i plan to increase light (on the cheap) i’m considering more bulbs or a 250HPS that runs on a 4-hr on-time. the idea is that natural daylight intensity in many places is only peaking for about 4 hours. i’ve heard other frugal growers say that staging wattage throughout the on-cycle saves $ and hardly affects yield.
my lights on at 4pm off 12pm(noon,20hrs on) because of the daytime heat.
I’m with you there, mine is running at almost 28C (82F) again today because of the heat here this summer. I usually aim for around 24C (75F), i find most strains are happy at that temperature and the risk of bud rot is reduced. It’s just not worth investing in A/C in here for all the time it would be running. I have worn out a few dehumidifiers over the years though.
I don’t think lights are even relevant compared to media and grow method used. Dwc in 88 degrees is a bad idea. Soil you can get away with it forsure led or hid. Yet 88 is still going so show more foxtails and spacy airy buds vs 80.
