Grow Temperatures VPD Chart Question

[Mike80]

Hey guys,

I’m following VPD chart for my grow. My humidity level is at 60% which allows me to have the temperature between 17 C and 22 C. My light on temperature is at about 21.5 C and light off is about 20.5 C. Should I drop the temperature during lights out even further ? I can lower my heater to drop the temperature to about 18-19 C or keep it the same at 20.5.

 

[Buds Buddy]

Hey guys,

I’m following VPD chart for my grow. My humidity level is at 60% which allows me to have the temperature between 17 C and 22 C. My light on temperature is at about 21.5 C and light off is about 20.5 C. Should I drop the temperature during lights out even further ? I can lower my heater to drop the temperature to about 18-19 C or keep it the same at 20.5.

Are you in Veg or Flower ? A lot of people lower their temps at the end of flower to bring out the Terpines & Colors.

 

[Mike80]

Are you in Veg or Flower ? A lot of people lower their temps at the end of flower to bring out the Terpines & Colors.

Hey I’m still in Veg. Plants are just sprouting from the soil. Week 1. Since I have the control over temperature just wondering if it would help the plant by lowering it further than 1 C at night

 

[Buds Buddy]

I personally don't use the VPD chart. I know in Veg 68 F - 80 F will be fine with 55% - 70% RH. In Flower I try to keep temps under 75 F & above 68 F with 35% - 55% RH. Seems to work just fine.

 

[Buds Buddy]

Seedlings like it a little warmer for the 1st couple weeks. Not sure of the F to C conversion but they say not to go under 68 F & no higher than 82 F. 77 F is suppose to be the perfect grow temp with lights on.

 

[Mike80]

Seedlings like it a little warmer for the 1st couple weeks. Not sure of the F to C conversion but they say not to go under 68 F & no higher than 82 F. 77 F is suppose to be the perfect grow temp with lights on.

I’ll start posting temperature conversions.
The lowest I can go according to the chart is 62.6 F and the highest is 71.6 F.

I’m currently maintaining 70.7 F during day time and 68.9 F at night. Should I lower it even further at night or just leave it as is. Is there a benefit to dropping temperature at night even further ?

 

[Mike80]

Seedlings like it a little warmer for the 1st couple weeks. Not sure of the F to C conversion but they say not to go under 68 F & no higher than 82 F. 77 F is suppose to be the perfect grow temp with lights on.

Since Im using the VPD chart, If I want a temperature at 77 F my humidity needs to be between 70-75 %. Bit high for my liking haha. The VPD chart seems legit, want to try sticking to it

 

[Buds Buddy]

Are you doing Hydro & talking about water temps ? That's what those temps sound like to me.

 

[Buds Buddy]

This Chart ?

 

[Mike80]

Are you doing Hydro & talking about water temps ? That's what those temps sound like to me.

I’m talking about air temperature for soil.

This Chart ?

Yeah I have another version of it but same idea

 

[Woblaaaah]

I dont get this chart if i have a temp of 45*C and humidity of 80% it's on the green? I thought that would kill your plants

 

[Buds Buddy]

F vers.

 

[Buds Buddy]

F vers.

45 C is what ? About 110 F ? I would think those temps would kill a plant. The way I understand it is these plants prefer certain temperature ranges & you're suppose to try to stay within those certain parameters. Too Hot or Too Cold & you don't get proper nutrient uptake or transpiration.
So you get your Temps & RH inline with what benefits the plants the most.
Lowering temps is usually done the last few weeks to enhance Terpines & Color which is a good thing too.

 

[Mike80]

I dont get this chart if i have a temp of 45*C and humidity of 80% it's on the green? I thought that would kill your plants

I don’t know if it would work but I wouldn’t use this chart like that. I would instead look at the humidity you are aiming for and then adjust the temperature according to the chart. Early Vegetation period I’m aiming for 60% humidity and over the course of two months I will reduce it to 40%. For example, if you want 50% humidity, you want your temperature to be between 59 F and 71.6 F to maximize your yield. You could grow without this chart and you will probably be fine, but if you want bigger yields I would stick to the chart.

F vers.

Thank you

45 C is what ? About 110 F ? I would think those temps would kill a plant. The way I understand it is these plants prefer certain temperature ranges & you're suppose to try to stay within those certain parameters. Too Hot or Too Cold & you don't get proper nutrient uptake or transpiration.
So you get your Temps & RH inline with what benefits the plants the most.
Lowering temps is usually done the last few weeks to enhance Terpines & Color which is a good thing too.

Yep only use this chart as a reference to what you are aiming for.

 

[Buds Buddy]

That's backwards. You have to adjust your humidity to your temps. Find out how hot your grow area gets & then you have to get the humidity correct to that temp. Higher temps make it harder to get High Humidity & Lower Temps make it easier. I sent you a PM I think might help.

 

[Mike80]

That's backwards. You have to adjust your humidity to your temps. Find out how hot your grow area gets & then you have to get the humidity correct to that temp. Higher temps make it harder to get High Humidity & Lower Temps make it easier. I sent you a PM I think might help.

Hey , thanks for the information. I’m able to control the temperature pretty well in my tent. I just have a target humidity that I want for my plants and I adjust temperature accordingly. It’s pretty easy for me to control temperature vs humidity. I got your PM, very helpful site thank you

 

[Buds Buddy]

Hey , thanks for the information. I’m able to control the temperature pretty well in my tent. I just have a target humidity that I want for my plants and I adjust temperature accordingly. It’s pretty easy for me to control temperature vs humidity. I got your PM, very helpful site thank you

You're welcome. I get a lot of my info there.

 

[Rosti]

Hey I might be able to give a little advice, as I use a VPD chart during my grows but I need a little information first. Which chart are you using exactly? Do you mind posting it so I can see what you see. You said you have complete control over the humidity and temp of your tent? What strains are you growing? Indicas, sativas?

Off the bat I can tell you that you will be better off running 65% humidity and around 75-78 degrees ambient temperature... usually your core leaf temp is about 2-3 degrees cooler then your ambient temp so take that into account when dialing it in. (You can get a laser thermometer for $20 if you want to be 100% sure) but your plants may actually grow slower, even though your within the VPD range, marijuana grows faster with slightly warmer temps. Go to cool and it slows down growth so you want to find a nice middle ground. But that’s where strains come into play, for example I would grow Durban poison in a hotter environment then I would say white widow (or any other strain) that prefers a more temperate, or cool environment.

 

[Mike80]

Hey I might be able to give a little advice, as I use a VPD chart during my grows but I need a little information first. Which chart are you using exactly? Do you mind posting it so I can see what you see. You said you have complete control over the humidity and temp of your tent? What strains are you growing? Indicas, sativas?

Off the bat I can tell you that you will be better off running 65% humidity and around 75-78 degrees ambient temperature... usually your core leaf temp is about 2-3 degrees cooler then your ambient temp so take that into account when dialing it in. (You can get a laser thermometer for $20 if you want to be 100% sure) but your plants may actually grow slower, even though your within the VPD range, marijuana grows faster with slightly warmer temps. Go to cool and it slows down growth so you want to find a nice middle ground. But that’s where strains come into play, for example I would grow Durban poison in a hotter environment then I would say white widow (or any other strain) that prefers a more temperate, or cool environment.

Hi Bubblin,

This is the chart I’m using below. I’m growing White Widow at the moment Indica strain. I’m currently maintaining about 60% humidity and my temperature with lights on is about 70.7 F and lights out 68.9 F. My basement is cold and has about 44% humidity without me doing anything . I have a heater outside the tent that automatically turns on/off according to room temperature and I have a humidifier in my tent that does the same thing.

 

[Mike80]

Hey I might be able to give a little advice, as I use a VPD chart during my grows but I need a little information first. Which chart are you using exactly? Do you mind posting it so I can see what you see. You said you have complete control over the humidity and temp of your tent? What strains are you growing? Indicas, sativas?

Off the bat I can tell you that you will be better off running 65% humidity and around 75-78 degrees ambient temperature... usually your core leaf temp is about 2-3 degrees cooler then your ambient temp so take that into account when dialing it in. (You can get a laser thermometer for $20 if you want to be 100% sure) but your plants may actually grow slower, even though your within the VPD range, marijuana grows faster with slightly warmer temps. Go to cool and it slows down growth so you want to find a nice middle ground. But that’s where strains come into play, for example I would grow Durban poison in a hotter environment then I would say white widow (or any other strain) that prefers a more temperate, or cool environment.

Your numbers match my chart for 65% humidity. I’ll increase the temperature to about 78 F and put humidity at 65%. Do you drop the humidity for the plants on a weekly bases?