Fall ‘24

You need to pay attention to the plants first and foremost. VPD can help guide you, because every plants going to have its own subtle ideal. but in general, if you are running high c0s than theoretically your ideal VPD would increase because you need to run he light at more intensity which requires higher humidity as well. You get to a point where the heat gets too hot and the stomata of the plant close, then photosynthesis stops.same happens if you have lack of co2. If you are running extra c02 in those ranges some people get in the upper 80s. Water uptake by the roots is going to change more than you should change humidity.you want her to be drinking from the roots. I would do what 001100010010011110 said and not change your target VPD too much. Just pay attention to your plants, they should be able to tell you what they need. it just gets hard to do if you change multiple things at one which it necessary when running extra co2. You may be able to find a few charts or videos of people out there and general numbers. A lot of the videos i have found are a little old with people using slightly older tech and sealed rooms which can be a little different than tent growing for sure.

Depending on the stage at which your plants are, you can go up to 1050ymol/ms with the CO2 content from 1200 to 1050ymol/ms and increase the temperature bias to 30 degrees, then the plants metabolize the CO2 very well. The vpd value is responsible for the growth of the plants due to the transpiration of the leaves. Increase the temperature should lower the relative air spruces. There are tables where you can read the ideal vpd value for each stage, which is calculated by room temperature and humidity.

Hello- vpd is just temperature and humidity. CO2 might affect humidity, but if you’re already controlling you’re good. CO2 benefit is more PPFD. CO2 helps photosynthesis. VPD is just transpiration. I believe you do need higher temperature to take advantage of the CO2 for photosynthesis though. So match your humidity to the target vpd with that ideal temperature.