Ideal temps and humidity with QuantumBoards

Hey guys i've been trying to perfect my setup to have better quality flowers, what is the ideal temperature and RH with lights on/off ? I've been reading a lot and found diverse information over the internet...

My setup is set this way (lights on):
- Temperature: 78.8F
- RH: 65%
- kPa: 1.18

Lights off:
- Temperature: 68F - 70F
- RH: 65%
- kPa: 0.88

It's important to tell that i'm using Samsung QuantumBoards so the leaf temperature is lower than room temperature which impacts on how my plants are transpiring... I don't have a laser thermometer yet but already ordered one from internet to know what is the exactly leaf temp of my setup...

A friend of mine who is more experienced than me and has almost the same setup (with QBs) told me that i should higher my temps to 85F and RH 75% at beginning of flower and lower it down after week 6 to 55% RH and 78F...

At the same time i've readed that lowering your humidity to numbers like 30%-40% at the end of the flowering + lower temps (70F) would boost the terpene production... That makes sense to me since most cannabis have influence of indicas from the himalayan region where the climate is cold and dry at harvest time... I think emerald triangle has the same characteristics too cold & dry...

So what do you guys think ? Tell me about your personal experiences and which range of temp/rh was the most efficient for you

I would raise the temp a little, I like mine around 82-83. And yes there’s so much info out there it’s hard to decide what to go with lol. Ive wondered the same thing about lowering temps at the end with led’s.

Veg= 85-87* / 70-75% Kpa close to 1
flower = 82-85* / 60-70% kpa close to 1.4
-- just a ballpark avg . Changes with how the plants are looking with each stage and airflow.
- if your airflow is on point then I'd raise your temps , regardless of plant stage

People told me that i should be at 80-85F range but i've readed that temps above 75f would degrade the terps but i dont know...

My thermal leaf temp readings I found have always been -2 , -3 * cooler than air temp.
Your reading for cmh or something other than led.. maybe your reading the cure? 75* with led isnt going to cut it imo ..

SBBCal said:

My thermal leaf temp readings I found have always been -2 , -3 * cooler than air temp.
Your reading for cmh or something other than led.. maybe your reading the cure? 75* with led isnt going to cut it imo ..

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Not even close. They will get sick. Stop up taking calcium.

Late stage flower ( last 1-2weeks) I lower the watts with temp/rh to about 80*-82 / 50-55% , which is about 1.4-1.5 kpa

secretsociety420 said:

People told me that i should be at 80-85F range but i've readed that temps above 75f would degrade the terps but i dont know...

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I'm sure you have one, just in case you don't.

SBBCal said:

My thermal leaf temp readings I found have always been -2 , -3 * cooler than air temp.
Your reading for cmh or something other than led.. maybe your reading the cure? 75* with led isnt going to cut it imo ..

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Could you explain why 75f wont make it ?

Photosynthesis

SBBCal said:

Photosynthesis

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So in your experience the temps should be higher ?

I don't understand why am i looking for higher, i mean why shouldn't grow lower terps low humidity ?

For an example if i grow 68F with RH at 40% i would be at 1.4 kPa, by the logic with that settings i would preserve the terps better, right ?

secretsociety420 said:

Could you explain why 75f wont make it ?

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The plants need the warmth for their metabolism. High light intensity and low temperatures make the plants unhappy. Their transpiration rates won't match up with their photons bombarding them.

But if they a re too cold they can't transpire like they need to calcium only comes up passively through the xylem by the water pressure the plant creates driving the water into the leafs. So if it's cold and they don't transpire enough they won't bring enough calcium up with them. And will get major calcium issues.

Guys just because a plant did well in a certain environment, it doesn't mean it's optimum or ideal.
For example with tomatoes..

Ask anyone who owns a multimillion dollar dutch greenhouse,

The ideal humidity in their case is 80%
Their ideal daytime temperature is 20c
Their ideal NIGHT time temperature is 20c too, as plants don't have to ADJUST to night time temps and just breeze through.
Of course they'll probably never get these ideal conditions because one thing counteracts another.

Now in nature, where does this happen?
Not saying it's ideal for cannabis. But natures environment doesn't always mean best.

i was thinking about switching to led those hlg lights look mint, i was having a similar thought the other day. so if your using hps/mh lighting your canopy temps are lower due to the ir light from the bulbs, but with led the canopy temp needs to be higher since there is no ir light coming from the leds. how do these canopy temps change for led when the plants are in co2 enriched room? thoughts?

xox said:

i was thinking about switching to led those hlg lights look mint, i was having a similar thought the other day. so if your using hps/mh lighting your canopy temps are lower due to the ir light from the bulbs, but with led the canopy temp needs to be higher since there is no ir light coming from the leds. how do these canopy temps change for led when the plants are in co2 enriched room? thoughts?

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Even hotter. But I noticed as they started budding a little cooler was better. The foliage felt better. But first 3 weeks of flower with CO2 I was running at 86-90*F and the stretch was epic. Lol.

Hey guys i came across a VPD / kPa calculator which gives me the kPa from the room and the kPa from the leaf... I was wondering what would be the optimal kPa for leaf ?

For an example:

secretsociety420 said:

Hey guys i came across a VPD / kPa calculator which gives me the kPa from the room and the kPa from the leaf... I was wondering what would be the optimal kPa for leaf ?

For an example:
View attachment 4941887

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A VPD of 1 is pretty easy on the plants. 1.5 is good in flower.