Temps with leds - Range

Skyhound

Well-Known Member
Guys for example , if i search on google for a good range of temperatures when flowering with HPS without co2 i can easily get an awnser , i have a range to work from 18c / 65f to 26c / 79f , if try to search for leds temps and ask on forums for a range of good temperatures , im only getting 28c / 83f is ideal , ok i get that , but is 22c / 71.6 f still in the ok range or will i have some sort of trouble , like :

Lower potency,
Lower flower volume
Less terpenes
deficiencies
 

Rocket Soul

Well-Known Member
You'll end up having problems if you try to give full flower intensity if your space is in the low 70s: cold plants will not be able to keep up with metabolism or transpiration. Lower yield and defs that are hard to correct without overdoing and causing lock out. With those temps I'd be looking into cmh.
 

Creature1969

Well-Known Member
68F average under COBs. I've seen as low as 64F. Hasn't been above 70 this grow. Hell, even the peppers and tomatoes are doing fine.
Ideal? No. Working fine. Yep! :bigjoint:
Had mildly slower growth in veg, no real difference in flower.

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OSBuds

Well-Known Member
"Plant growth and development is primarily influenced by temperatures at the growing points of plants (i.e., roots and shoot tips). When we are discussing temperature, it is important to understand that plant temperature (not air temperature) drives physio-logical responses in plants. Air temperature can differ by as much as 10° F from plant temperature, depending on your light source (HPS, MH, or LED), light intensity, humidity, and air speed. For example, HPS lights emit a large percentage of their energy in the infrared (IR) range (800nm–1000nm) which is not photosynthetically active yet significantly increases plant temperature. As a result, growers need to decrease their air temperature set-point to counter the additional radiant heat."
 

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ҖҗlegilizeitҗҖ

Well-Known Member
LEDs have a lower IR spectrum so the leaf surface temperature stays lower than with HPS light.
That's why temps generally should stay higher with LEDs.
80° or so is good for the day
75 is fine
70 will slow growth for daytime temps.
Night time it doesn't matter though as long as you try and stay within 10° of the day temps
 

Norml56

Well-Known Member
Guys for example , if i search on google for a good range of temperatures when flowering with HPS without co2 i can easily get an awnser , i have a range to work from 18c / 65f to 26c / 79f , if try to search for leds temps and ask on forums for a range of good temperatures , im only getting 28c / 83f is ideal , ok i get that , but is 22c / 71.6 f still in the ok range or will i have some sort of trouble , like :

Lower potency,
Lower flower volume
Less terpenes
deficiencies
lol clear as mud?
 
In my experience growing indoors with Chilledpuck LED builds is that the leaf temperature throughout my flowering canopy is on average -4.5f compared to the room's air temperature. Compared to when I used to grow with HID lighting, the leaf temperature would be from -0f to -2f at most. This doesn't sound like a significant difference however I grew several cycles with LEDs before deciding to try higher flowering temperatures to see if I could get the yields that I used to get under HID and in doing so I found the results that I was looking for when initially switching to LED: Improved quality AND quantity.

Initially, upon switching from HID growing to LED growing, I was using all of the same environmental parameters with the LEDs as I was with the HIDs except for having even more intense light at 1500ppfd average with the LEDs vs 1000ppfd average across the canopy before with the HIDs. To me, this meant I should have bigger and denser buds, a higher per plant yield, and faster overall growth rates. My results with using all of the same equipment in the same environment and same parameters were only slightly improved and overall, disappointing. However, after raising the temperature of each week of the grow cycle by +4f and properly calculating the leaf vpd using an IR thermometer, I found much-improved success in all areas.

I achieved my success by raising all growth stage room temperatures from 80f week 1 to 72 week 9 with the HIDs to 84 week 1 and 76f week 9 with the LEDs, for example. I believe that this "General Recommendation" grow environment parameters chart (https://cch2o.com/general-recommendations/) was designed with HIDs in mind (-2f leaf differential temperature) as the leaf vpd comes in at 1.19kpa week 1 after calculating vpd in kpa using a leaf temperature of 78f and 60% RH. The chart finished with a week 9 leaf vpd at 72f (room temp) and 40% RH and a leaf vpd of 1.45kpa (-2f leaf temperature).

Today, I still follow this chart and find it to produce pristine results with the only change of increasing the weekly room temperature values in all stages and weeks of growth to +4f and adjusting the RH at each week to follow a vpd cycle that I have found works best for my plants in my system. For example, for week one of veg I run my LED grow room at 86F and 65% RH. By using this VPD calculator: https://pulsegrow.com/pages/vpd-calculator, the leaf vpd can be found to equal 0.98kpa using a leaf differential temperature of -4f. I have found that once a plant has matured into the vegetative stage having at least 3 or 4 sets of side branches, that growth rates are best with a leaf vpd of about 1.0kpa. As the plants' life stages advance into flower I gradually increase the leaf vpd all the way to 1.45 at week 9 of flower.

In order to achieve the results that I am with your LEDs, I recommend using an IR thermometer to measure your leaf temperatures all over your canopy at mid-day (lights on) and find the average value. Then look at what your room temperature is averaging during that time and find the difference. Use these values in the VPD calculator that I shared with you to determine how you need to program your AC and Dehuey to achieve the VPD appropriate for your plants' stage of growth. I find that 0.70 kpa is best for clones and seedlings, 1.0 kpa is best for veg and 1.3 kpa is best for flower. I do not monitor the vpd at night as I find that to not be cost effective. I have not conducted any experiments but I predict that the improvement in results I would get by running an extremely oversized condensation dehuey or even a desiccant dehuey would not even be close to worth it. My rooms do not get above 50% RH at night at any stage of growth and that is all that I conern myself with regarding night vpd currently.

I hope this post can help growers using LEDs to get the most out of them. I have seen other LED growers post online that they have also found success using higher temperatures as the LEDs produce less IR radiation and offer less heat to the plants' leaves and this is best to be compensated for by increasing room temperatures. As previously mentioned my vegging plants grow like mad in my ebb n flow hydroton system with LEDs and a day room temperature of 86f and RH of 65%. Urbanremo on youtube and my IR thermometer both worked in conjuntion to solidify my decision to experiment with the increased room temperatures and I do not look back. Urbanremo, in a recent LED garden update of his in his flower room, stated that he finished his plants at 78f (presumed room temperature) and he has much less light on his plants than I did and my buds were not nearly the same size! Raise those temps and maintain proper vpd and I bet your results will improve!

Happy growing!


TLDR: I increased my room's temps +4f from what I would be using with HID to achieve the best results!
 
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