VPD THREAD? Vapor Pressure Deficit information needed!!

[Deathpack]

I like vpd as a rough guide, just do go nuts chasing it like its the word of the lord, its a guide... the concept makes perfect sense. What i do is try to roughly follow it until about 3 weeks from finish, then use a week to transition to bone dry and cool finish. Remeber vpd concept is for overall plant health, your goal in last few weeks isnt overall plant health, as shea done growing as a plant, you now want conditions ideal for bud finishing and ripening..

Thanks for the feedback... great info , will be sure to keep in mind!

 

[Huckster79]

I was a nube like you, i wanted more of a goal than just finish w live plant and a nug... i did all sorts of shit my first grow and learned lots by diving in deep... my best advice is triangulate off all the diff advice you get to make your own style, take nothing to extreme, do ny change slow, and ignore ppl's advice who tout their way as the only way..

I think part of it is if your into botany youve grown something else before, many new growers have never grown a marigold so the simple get to finish w a smokable nug may be a solid goal for them...

 

[ruwtz]

It's good to add CO2 in any stage of any plants life , helps with growth if you know what you're doing.. the only CO2 my girls are getting are from their bedtime stories haha, until i set everything up this weekend haha!

Not true. Ambient CO2 levels - typically 400ppm - in veg are more than sufficient.

Elevated CO2 levels restricts stomata density https://www.sciencedaily.com/releases/2011/03/110303111624.htm

Elevated CO2 levels constrain nitrogen acquisition
http://onlinelibrary.wiley.com/doi/10.1111/gcb.12938/abstract

 

[Shugglet]

Not true. Ambient CO2 levels - typically 400ppm - in veg are more than sufficient.

Elevated CO2 levels restricts stomata density https://www.sciencedaily.com/releases/2011/03/110303111624.htm

Elevated CO2 levels constrain nitrogen acquisition
http://onlinelibrary.wiley.com/doi/10.1111/gcb.12938/abstract

The problem I have with the first study is that, if youre running CO2 at 1000-1500 ppm, you are 2-3x higher concentration levels than natural. Even if stomata density is reduced by ~30%(varies by plant) I would think the fact youre dealing with a 100-200% increase in co2 level would result in a net increase in available usable CO2 to the plant assuming no other bottlenecks. So in other words, while 400 probably is sufficient, elevated will increase the overall potential.

Also a good reason why people running CO2 run higher temps, because they open the stomata.

 

[ruwtz]

The problem I have with the first study is that, if youre running CO2 at 1000-1500 ppm, you are 2-3x higher concentration levels than natural. Even if stomata density is reduced by ~30%(varies by plant) I would think the fact youre dealing with a 100-200% increase in co2 level would result in a net increase in available usable CO2 to the plant assuming no other bottlenecks. So in other words, while 400 probably is sufficient, elevated will increase the overall potential.

Also a good reason why people running CO2 run higher temps, because they open the stomata.

Interesting presumption, and worthy of some testing if you're up for it.

Also, higher temps with CO2 are beneficial due to increased rapidity of metabolic processes, not necessarily opening stomata. In fact, under water stress, stomata will just as easily close at higher temps.

 

[pop22]

I'd shoot myself before having all that crap in my growroom! If I wanting to work in a lab, I'd get a job in one! Growing at home isn't all about the almight gpw, its really about quality and the enjoyment of watching your plants develop.

But to each his own, that's simply my feelings on it, so if you enjoy this style of growing, cool! I hope it brings you satisfaction! Myself, the simpler I can make my grow, the better.

You are putting in the right effort to control your grow environment. The more control you have the better grower you will be. I recommend a data logger. I use a Sensorpush $50. There are others. Maybe be better ones. Havent looked in awhile. They are temp/hum sensors that send text to your phone if it falls out side the hi/low settings. The app provides a nice graph chart hour, day, week, month, year.

 

[Jaybodankly]

"If youre running CO2 at 1000-1500 ppm, you are 2-3x higher concentration levels than natural".

My understanding is plants evolved under much higher levels of CO2 and heat for millions of years. Growing indoor is not natural. Creating better conditions for perfect growth than available outside is not natural. Creating an excellent growing environment is what we strive to do.

 

[whitebb2727]

I've never worried about vpd. I actually prefer my humidity lower than most recommend. 40% range.

 

[ChaosHunter]

 

[Huckster79]

Id say the range given for late veg should be carried through the begining of flower, say 3 or 4 weeks even... lowers the stress of the flip as one less change, but i think really helps em grow in that rapid stage of development, once plant starts to be relatively fully formed and further growth will be more in a swelling and enlarging type of growth vs fresh new growrth then transition to drier and drier air... there is zero reason that rh needs to drop the night of the flip...but finish dry oh hell yea.. and a drop in temp to i prefer towards the end... i do my temp like i do my humidity dont change it day of flip... give it that warmth for the growing part of flower and cool temps w bone dry air... god i can almost taste the results of that just thinking about it... time to quit just thinking about it

 

[Heber]

Hello,


I am a beginner level grower, and am taking on my first rodeo hahaha...after months of observation, years of connoisseuring and lifetime love for all things botany. I've decided to take on a few methods that most growers do not practice... I've been reading up on transpiration, and have been looking for ways to keep my VEG room on point when it comes to how much moisture is in the air.. i've added some humidifiers to the rooms , and am constantly checking temps/RH to make sure i don't step foot into a danger zone... ANY TIPS?

MAIN VEG - 75* F
51% RH

ROOM 1 - 80* F
53 % RH

Note: I transplanted a few plants from veg (at about 2 - 2 1/2 feet tall) into 15 gallon smart pots.. I plan to veg them for another 2-4 weeks..


Any help or tips would be greatly appreciated...


~ death

Vpd range u r shooting for is different thru different cycles. 1-4 for early veg, 4-8 late veg, 12-14 early/mid flower, 16-17 late flower here's a chart

 

[Heber]

The problem I have with the first study is that, if youre running CO2 at 1000-1500 ppm, you are 2-3x higher concentration levels than natural. Even if stomata density is reduced by ~30%(varies by plant) I would think the fact youre dealing with a 100-200% increase in co2 level would result in a net increase in available usable CO2 to the plant assuming no other bottlenecks. So in other words, while 400 probably is sufficient, elevated will increase the overall potential.

Also a good reason why people running CO2 run higher temps, because they open the stomata.

High co2 levels actually temper the atomata openings , with the plant thinking it has enough co2 uptake, same reason plants grown under elevated co2 have lower stomata density... if plants are grown at atmospheric co2 thru veg (when leaves r forming)theoretically they will have normal stomata density... also, just my own theory I'm testing, reducing co2 to ambient half (600-700)of normal I run, for 7 days following defoliation (will keep posted on that)

 

[Kami Samurai]

Bump about to share the vpd information I’ve read.

 

[ANC]

I make sure to photograph my plants along with the meter readings when I am happy with their performance.