The Dude Grows Show

Leaf temp vs. room temp

I have recently learned during my latest class at “weed” college, that leaf temperature is more important than the par amount. This just doesn’t seem correct, what do you guys think? Instructor stated the “sweet spot” for leaf temp was 85 f . I would have to maintain a ambient temp of 90-95 f to get a leaf temp of 85 f. Maybe for some sativa cultivars but definitely most indicas would suffer from that much heat. By the way, can’t wait to get some more genetics from you guys once I get my next paycheck!! Last batch was outstanding!

Thanks Dudes!,


4 responses to “Leaf temp vs. room temp”

  1. jmystro Avatar

    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.

  2. BudHuntersGuild Avatar

    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

  3. BudHuntersGuild Avatar

    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

  4. Sunnyinbectopia Avatar

    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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