VPD Adjustment

This time, I plan to use a VPD chart during the growth process.

As a proof of concept (POC), I set up a Raspberry Pi with DHT22 sensors to read temperature and humidity data. Based on this data, I calculate the VPD (air). Additionally, I use two adjusted parameters: VPD (leaf) at -2°C and +2°C compared to the current air temperature.

The application exposes metrics and calculated values, which are collected by Prometheus and displayed on a Grafana dashboard.

On the dashboard, there are data/graphs for three growth stages, along with a calculation of how much humidity needs to be adjusted in the given situation (based on VPD air, leaf -2, and leaf +2).

How well this works in practice remains to be seen. However, this is definitely the fastest way to determine if you're on the right track when following the VPD chart.

This is how my dashboard looks like:

Look at this, if you have the money to spend it could be a game changer,


They're designed to integrate with their controller to control light intensity as the leaf overheats, but I'm sure someone with your tech savvy could have it control other parameters like air temp/co2/humidity

I can not see prices but those gadgeds are usually expensive.
I have a plan (not sure when) to integrate IR temp sensor for leaf, there are quite cheap options (mlx90614 or mlx90615 temperature sensor with various lens addons (extending the range of sensor)).

sebs999 said:

I can not see prices but those gadgeds are usually expensive.
I have a plan (not sure when) to integrate IR temp sensor for leaf, there are quite cheap options (mlx90614 or mlx90615 temperature sensor with various lens addons (extending the range of sensor)).

Click to expand...

I think it's a couple hundered British pounds, I'm not sure exactly how it works but it takes an average canopy temperature, most I've seen only measure a single fixed point.

Even planes have a simpler interface lol
You don't need to follow VPD so tightly, you just need to remember these basic rules
At any given time, veg or flowering:
High Temps - High RH
Low Temps - Low RH
Good luck

DanKiller said:

Even planes have a simpler interface lol
You don't need to follow VPD so tightly, you just need to remember these basic rules
At any given time, veg or flowering:
High Temps - High RH
Low Temps - Low RH
Good luck

Click to expand...

of course we all know basic rules, I have been growing inside for ~20 years, but there was a lot of studies regarding VPD and why not try to achive maximum potencial for them.

The margins between being exactly on the VPD number or in the range of that number is so small, it's really going after the 2-3% difference if any.

DanKiller said:

The margins between being exactly on the VPD number or in the range of that number is so small, it's really going after the 2-3% difference if any.

Click to expand...

There are a bunch of different things we can control to give us 2-3% increases in whatever, when we add them all up it might be a 15% increase overall, that's huge.