I have a good topic here! How many of you use VPD for your set up? Why?
How many people don’t even know what that is? Lol!
How many people are like us and don’t really pay attention to VPD? Lol! Why?
The reason We don’t is it’s a pain in the butt to dial it in perfectly. You literally need ac, heater, humidifiers, dehumidifier, exhaust fan etc. That’s doing to much for our set up. I will say that learning about VPD helps you to understand the importance of temp and humidity in your room.
same here - first became aware of it a couple years ago using the ac infinity app and controller, read into it more and tried keeping it optimized but it fluctuates a lot and i can’t quite do much about it in the current config, so i just look at the plants to see what they need and they always seem happy regardless!
thanks for posting this @SweetsensiWA - its very reassuring reading these replies! and i agree, even tho i can’t quite dial it in perfectly it helped me understand temp / humidity factors a lot more and i know how to interpret signs from the plants better as a result and at least make whatever adjustments i can in the moment
just be aware of temp and humidity, chasing vpd takes a lot of controls that small setups have a hard time with. if temp or humidity is way off do something to correct, cannabis if pretty forgiving. also watch humidity right at lights off, will really go up good to vent hard.
VPD is all about plants breathing. Our plants leaves have pores called stomata. If it’s too dry, they close them to retain moisture and draw more from their roots. If your EC is too high at this point, it could spell disaster for your grow. If it’s too wet, and you’re in the flowering stage, you’ll likely get bud rot. Since transpiration impacts photosynthesis, respiration and nutrient uptake, VPD is a key factor for optimizing plant growth.
Ngl, for me, VPD presents a challenge; if it’s 83 F in the tent, and I need 55% humidity, but my environmental RH is only 19% on average, it’s really difficult to be wet. That’s my negative humidity problem. I mean, most of the year in So Cal we only need humidifiers… in every room in the house, lol. Adding to that, if the exhaust fan comes on and it’s 20% RH, the tent dries out and humidifier works overtime. We literally go through 5 gal of RO water a day, just in humidifiers; 2 in the grow, and 3 throughout the house, just to keep us at around 30% RH.
Then there is drift. Not the cool car kind, but the temp/RH kind. You can’t just say “VPD is 1.2”; it only works like that with AI controllers and all the accessories.
Pro Tip: You can calculate averages and be much closer than those who don’t; you can say “my temps run between 79 and 82 F, so I need an average of 55% RH during mid to late flower, which puts VPD between 1.3 and 1.6 kPa”.
So yeah, for me VPD works, as long as I can keep the tanks filled.
I never really took into account the varying temps and humidity in different areas of the world. Makes sense why you use alot of water. In a way I think its cool how we all make it work with all the different variables. The science behind all this is very fascinating to me
I got mars hydro fan/filter i just turn up/down manually lol non stop checking but for me I like it it keeps u on ur toes and not lacking like all the automated stuff today…now mine reads 77°/55%rh 3-4 hrs it’ll be 72/52
Yep. In Florida, we had to run the house A/C 24x7x340-350 just to live there in what we called “the humiture”. So inside it was basically 50% humidity all the time. I worked with that fairly well without having to get a dehumidifier for the tent.
I don’t personally calculate VPD, or have a controller.
To me VPD is a byproduct of correct environment parameters, and should only be worried about when crop steering.
Once you dial optimal temps then you can just set humidity you want for the stage of growth. I need to dehu, others will need to humidify.
People misunderstand VPD a lot, if you try to use it to set your environment you can get very bad results or end up chasing your tail.
and at least make whatever adjustments i can in the moment
