Vpd vapor pressure deficit/ update

[Neverfold420]

A fellow grower posted on this subject (aquaman). This is a chart that exsplains how important humidity In comparison to the temp of you grow room. Here are results from dialing in and the results are grand exsploding growth.

 

[Aqua Man]

A fellow grower posted on this subject (aquaman). This is a chart that exsplains how important humidity In comparison to the temp of you grow room. Here are results from dialing in and the results are grand exsploding growth.

Glad it's working out for ya bro. I found it extremely helpful and important in hydro. One thing I have picked up since posting was it's not as effective in wet/dry cycle media like soil bit still very important.

But wow does it make a difference in hydro.

 

[Neverfold420]

Should i leave my girls in transition nutes till strech over?

 

[Aqua Man]

Should i leave my girls in transition nutes till strech over?

yes

 

[BillFarthing]

VPD is neat. I think you have to get surface leaf temps at the canopy for it to be accurate. If you run VPD after week 4-5 of flower you are asking for mold problems.

 

[Aqua Man]

VPD is neat. I think you have to get surface leaf temps at the canopy for it to be accurate. If you run VPD after week 4-5 of flower you are asking for mold problems.

I disagree. There is ideal VPD for different stages of growth but you are 100% correct you need to take leaf temps into account

 

[BillFarthing]

There is ideal VPD for different stages of growth

And VPD is all theoretical. If you run VPD with a strain with dense buds, you are inviting botrytis to the party. If you don't deleaf heavily and have excellent air circulation, you are inviting PM. Communism works in theory too!

Starting week 4-5 of flower, I would just keep the humidity 45-55%.

 

[Aqua Man]

And VPD is all theoretical. If you run VPD with a strain with dense buds, you are inviting botrytis to the party. If you don't deleaf heavily and have excellent air circulation, you are inviting PM. Communism works in theory too!

Starting week 4-5 of flower, I would just keep the humidity 45-55%.

It's not theoretical. I understand it quite well. I think you are going by generic charts and not actual VPD for different stages you seem to be confused as with proper VPD in late flower goes along the lines of exactly what you said for humidity but you neglect the air and leaf temps. Proper air circulation is always key and where pm is usually caused is the humidity spike after lights out as the temps drop. Not the daytime humidity of say 45-50% bit the spike of 70% ish after lights out in cooler temps

Maybe take a read of a pair I did to see what I'm saying.

This has nothing to do with Communism so you can leave the sarcastic BS out please

VPD (vapor pressure deficit)

Ok i was gonna sit down and write out a whole article but i have been lazy so instead instead I'm going to copy paste because im lazy. This is not my work so let start. You may find this very long but its worth the read. Some may want to skip ahead. I have added here and there to what i feel is...

www.thcfarmer.com

 

[BillFarthing]

It's not theoretical. I understand it quite well. I think you are going by generic charts and not actual VPD for different stages you seem to be confused as with proper VPD in late flower goes along the lines of exactly what you said for humidity but you neglect the air and leaf temps. Proper air circulation is always key and where pm is usually caused is the humidity spike after lights out as the temps drop. Not the daytime humidity of say 45-50% bit the spike of 70% ish after lights out in cooler temps

Maybe take a read of a pair I did to see what I'm saying.

This has nothing to do with Communism so you can leave the sarcastic BS out please

VPD (vapor pressure deficit)

Ok i was gonna sit down and write out a whole article but i have been lazy so instead instead I'm going to copy paste because im lazy. This is not my work so let start. You may find this very long but its worth the read. Some may want to skip ahead. I have added here and there to what i feel is...

www.thcfarmer.com

I appreciate your posts. I didn't mean to come off as abrasive. You are obviously smart when it comes to the garden. That said, we are going to have to agree to disagree.

I have seen VPD cause a lot of problems for seasoned growers, including myself. With larger well designed rooms, small localized changes in environment happen. If it works for you, great. I guess if anything else, I hope to point out a couple potential pitfalls with getting the "perfect" environment when dialing in a grow space.

 

[Aqua Man]

I appreciate your posts. I didn't mean to come off as abrasive. You are obviously smart when it comes to the garden. That said, we are going to have to agree to disagree.

I have seen VPD cause a lot of problems for seasoned growers, including myself. With larger well designed rooms, small localized changes in environment happen. If it works for you, great. I guess if anything else, I hope to point out a couple potential pitfalls with getting the "perfect" environment when dialing in a grow space.

Plain and simple because it was used wrong. Look at the VPD for stages of growth and actually calculate it. I bet you will see that it's almost identical to what you are doing.

There is a link in that thread to a calculator. If you punch in the leaf temps humidity and air temps. Then late flower you want a KPA of about 1.3-1.5

To give you an idea

75 air temp.
45% humidity
72 leaf temps

Equals a KPA of 1.45

Still think you did it right if you had an issue? It's very common people use it wrong. Look in my post again for the ideal KPA/VPD for the different stages of growth

 

[BillFarthing]

Plain and simple because it was used wrong. Look at the VPD for stages of growth and actually calculate it. I bet you will see that it's almost identical to what you are doing.

There is a link in that thread to a calculator. If you punch in the leaf temps humidity and air temps. Then late flower you want a KPA of about 1.3-1.5

To give you an idea

75 air temp.
45% humidity
72 leaf temps

Equals a KPA of 1.45

Still think you did it right if you had an issue? It's very common people use it wrong. Look in my post again for the ideal KPA/VPD for the different stages of growth

This whole formula assumes that grow rooms are a monolithic environment in theory. There are always going to be small changes in environment causing localized variables. These can include the placement of humidification control, radiant heat at the canopy versus underneath the canopy with HID lights etc. These variables cause problems that aren't accounted for in the formula that can cause a lot of headaches.

Is it a perfect formula? Nope. Is it a good goal to aim towards for maximum plant yield? Absolutely.

I'm glad I could chat with you about this today. I'm going to shut up and sit back and follow your thread and try to keep on learning.

 

[Aqua Man]

This whole formula assumes that grow rooms are a monolithic environment in theory. There are always going to be small changes in environment causing localized variables. These can include the placement of humidification control, radiant heat at the canopy versus underneath the canopy with HID lights etc. These variables cause problems that aren't accounted for in the formula that can cause a lot of headaches.

Is it a perfect formula? Nope. Is it a good goal to aim towards for maximum plant yield? Absolutely.

I'm glad I could chat with you about this today. I'm going to shut up and sit back and follow your thread and try to keep on learning.

I agree but that is the same with any grow room and proper placement of equipment and proper equipment is important. One common mistake is as simple as thermometer placement. Like any measuring equipment proper usage is key and like any say computer model the accuracy of the information put in will affect the accuracy of info out... Garbage in equals garage out.

 

[AnselAdams]

I disagree. There is ideal VPD for different stages of growth but you are 100% correct you need to take leaf temps into account

This has been my limited experience growing hydro in cabinets as well. Lower VPD numbers during germ & grow; and progressively higher numbers a the plants bulk out. I found the trick to be in monitoring the factors. A nice piece of tech, helps me with that a lot.