In the Weeds • October 04, 2021
Timing Your Drybacks
All right, so this is a graph from one of my hoop houses. You can see in here that I'm ramping my water content up to match the climbing VPD. This way. I have no water stress on my plants. If you don't get your water content up fast while you're having your VPD climb, you will see water stress. It was 90 degrees yesterday so you get an idea that it gets hot as fuck out here.
Now, what I'm trying to do is I'm trying to achieve my dry back within two hours before the sunset. So you could see from 4:00 to 6:00, I go from a 60% down to 40% water content, so I basically achieved my full dry back during that period. From this point around 6:00 PM when the sun is setting, it's usually around like 7:00 the sun sets, then you could see my irrigation, my dry back kind of flat lines, it doesn't do much. So if I don't achieve that dry back while the sun is still up, I won't get the dry back I'm looking for and I won't be able to pump my plants. This is really important to understand, because you want to make sure you're at peak saturation during peak VPD, but achieving your dry back before the sun sets or else you're going to have a lot of mold issues.
I hope this is helpful. This is just a few concepts that I like going over when I'm looking at my graphs. Let me know your thoughts. Peace.