On indoor growing, when you increase light intensity, do you change VPD?
My Tutankhamon’s VPD generally kept around 1.0-1.1 kPa, but I’ve just gone up from c. 600 PPFD (18 hours) to around 750 PPFD, and the leaves are a little lighter green today.
I don’t know whether to increase humidity (so slower water uptake but more efficient mineral usage) or decrease humidity (higher water uptake but might also suck up more minerals than it can consume).
Any experience or advice to share?
Hello and welcome to the community i hope you enjoy it here and great question. And i believe you would want to increase vpd with light intensity but at a very small amount. Veg vpd range is around 1.0-1.1 depending on who ya ask and for flowering you can scale from 1.0-1.5 vpd with 1.3 being a sweet spot but ya wont need to go any higher than 1.5 regardless as long as your not pushing like 1200 par. Co2 also plays a factor when increasing light intensity, as intensity gets stronger plant is drinking and exchanging co2 more than normal so if lacking the extra co2 it may not make much of a difference increasing light and/or possibly harming the plants growth. As for adjustments i find it alot easier (for my grow setup) to chase humidity levels rather than temp levels as long as im not pushing my humidity passed 77% in the grow room. High 80 temps or higher ya may want to try and lower to at least low 80s or mid to high 70s if possible and this will keep you from having to go above 77% rh and possibly risking mold and mildew. During flowering time youll def want to try and keep your temps in mid to low 70s so you can keep your rh in the low 60s and also not risk mold or mildew. And if its challenging to maintain or get to these levels, having good airflow and exchange will help a lot with prevention. Lol my bad for some rambling but yes overall tinker with rh and temps to try and keep vpd in-between 1.0-1.5. Veg better towards 1.0 and flower better towards 1.3 hope this helps ya a little and if you have any more questions dont hesitate to ask and happy growing
@Smokey101 covered that one really well, i do basically the same just adjusting humidity to try to balance vpd but my question is regardless of your 1.1kpa what is your temp and humidity like? Also what stage is the plant at? What you need to adjust or not could be completely different depending on the stage the plant is at in life.