Temps

my temps in my flowering room are 86 at the highest during lights in and 75 the lowest during lights off do these temps sound good to anyone out there???? I have 2 thousand watts and a 8000 BTU AC . someone at my local shop told me 84 on and 68 off would be good is this correct or not?

Plants are versatile and can take a lot of variation. Personally I use 86 as the high and 80 as the low during lights on. This is in the direct light beam at the top of the plant, ambient varies quite a bit depending on airflow and spectrum.
When the lights are off it gets as low as 55 every night without any noticeable loss of growth.
Over the years I have observed very little growth occurs under 70 degrees, even with strong lighting. No practical growth at all under 60 degrees.

In my personal opinion 86 is a little to hot, In less you are running co2. If you have good air flow and circulation you should be ok. Silica can help plants deal with higher temperatures. I prefer to keep it at 80 or so.

Depends if there's adequate air circulation and moderate humidity levels. Outdoors, we've grown in 105F heat in the midst of summer and with adequate water, it was not profoundly impactful.
Indoors....probably more air circulation or exhaust relieving the heat build up would help, but other indoor environmental factors should be considered.

Plants can be quite resilient. If they are green and healthy....they're fine.

Your temps are fine.

Best vibes to your grow!

Pics?

Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions


https://www.ncbi.nlm.nih.gov/pmc/arti...Article_27.pdf

ABSTRACT :

Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m−2s−1), temperatures (20, 25, 30, 35 and 40 °C) and CO2 concentrations (250, 350, 450, 550, 650 and 750 μmol mol−1) on gas and water vapour exchange characteristics of Cannabis sativa L. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (PN) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m−2s−1 PPFD and decreased at higher light levels. The maximum rate of photosynthesis (PN max) was observed at 30 °C and under 1500 μmol m−2s−1 PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m−2s−1 and 40 °C). Similar to E, leaf stomatal conductance (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN and WUE. A continuous decrease in intercellular CO2 concentration (Ci) and therefore, in the ratio of intercellular CO2 to ambient CO2 concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m−2s−1. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m−2s−1 respectively. Furthermore, plants were also exposed to different concentrations of CO2 (250, 350, 450, 550, 650 and 750 μmol mol−1) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and gs increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO2 (350 μmol mol−1) level. Elevated CO2 concentration (750 μmol mol−1) suppressed E and gs ∼ 29% and 42% respectively, and stimulated PN, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO2 concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m−2s−1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2 concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment.

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30C = 86 F

You should go on youtube and look at information on "vapor pressure deficit" it will help you out with your temps/RH

packerfan79 said:

In my personal opinion 86 is a little to hot, In less you are running co2. If you have good air flow and circulation you should be ok. Silica can help plants deal with higher temperatures. I prefer to keep it at 80 or so.

Click to expand...

seconds to this... You didnt specify what type of lights you were running, LED, CMH, HPS etc.. the reason I say this is That there is alot of information that with leds you can run your temps a bit higher 80-85F because the actual leave surface temperature doesnt heat up as much compared to HPS.


with 2k you should definitely be running Co2, that is one way your girls can positively absorb all that light you are throwing at her.

I use full spectrum leds (Fluence) and my girls thrive in temps around 78-81 and RH% at 60-63%


VPD VPD VPD!!!

iaM using HPS would like to lower my temps but if it isn't necessary I wont prefereably to 80 or 78 as I don't use silica and I think my plants usually reach at the most 2ft away from my lights after there stretch. I always read in the internet 75 is your ideal temperature. I don't use CO2 for the whole grow only first 3 weeks. my local grow store owners tell me as long as you are comfortable in your room it should be okay{as in not to hot or cold} temps right now are 84 hottest [no dehumidifier on] humidity 54 iam going to start flowering soon will be my second try with SCROG which I am still trying to get the hang of

Just to toss a wrench in the mess...

I run a lower VPD and the opposite of what most use. My preferred environment is a max 72F canopy temp and 15-20%RH. The terpene production and preservation is ridiculous. You will have to veg larger since the yield is a bit lower.

Welcome to the wild, wild world of cannabis cultivation.

Lower temperatures mean fewer mites, if that's a problem for you. I like to stay around 77F. Same temp my home thermostat is on. I run a perpetual grow so, it works for all stages of growth.

Cooler temps in late bloom bring out the purple in my pre98 bk.

i run a high of 85-86 but can hit 90 if im running all three bulbs (just in veg)
usually 77 on lights out during the day