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4 responses to “Leaf temp vs. room temp”

1. 

   jmystro

   07/18/2021

   Photosynthetic active radiation (PAR) relates to light spectrum, not temperature. Room temp is not an accurate measurement of the temperature on and around the leaf surface. IR spectrum is out of the PAR range and is a heat source that can raise leaf surface temp.

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2. 

   BudHuntersGuild

   07/20/2021

   I don’t know if i’d say leaf temperature is more important than PPFD but it does play a significant role in plant health. Basically the VPD effects the stomata and whether its opened too much, closed too much or in the optimal range for plant growth. If the VPD is to high, the plant senses a dryness and closes its pores to preserve water. If the VPD is to low the stomata opens allowing more water to flow through the plant which can lead to increased uptake in nutrients sometimes resulting in nutrient burn. If you’re in the general range of 1.0 to 1.6 you should be fine. A plant with a PPFD of 800 at that range will do significantly better than the same plant with same VPD range but a much lower or even higher PPFD

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3. 

   BudHuntersGuild

   07/20/2021

   For what its worth i’m growing an indica dominant hybrid and my leaf temp is -5 from ambient air temp. My tent runs at 89-93 degrees. I keep the humidity higher to keep the VPD at my target of 1.3. Once I flip to flower I will be lowering the RH so my VPD is in the 1.5-1.7 range

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4. 

   Sunnyinbectopia

   11/19/2023

   Thanks for the reminder, I need to get my temperature gun back from Randy! Because I forget to check Lisa temperature. I take it for granted that it’s whatever the room is. But it’s not. Thanks.

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