Leaf temperature

So, I typically hang my sensor underneath my grow light (LED) and as close to the top of the canopy(s) as possible. I am experimenting with higher humidity/temps, as my focus has shifted to VPD the past year or so. Recently, I have been taking leaf temps with an IR thermometer. I have noticed that the leaf temps are approx. 5º to 6º cooler than what the sensor is displaying, even though the sensor is right above/at the canopy. Is it recommended, or does anyone offset their sensor temps to reflect leaf temperature rather than the ambient temp of the tent, even if the sensor is right near the canopy? Just curious regarding people’s results if they have done/do this.

1 Like

Mine is -2°

I suggest moving your IR thermometer closer to the leaf surface - like 1 to 2 inches - to measure leaf temps.

1 Like

That makes sense. I didn’t even consider how the plastic housing of the sensor responds to heat vs the leaves. Thanks and much appreciated. :+1:t2:

Your right. Your leaf temperature is what it is. Temperature offset is the difference between ambient and leaf temperature. I’ve had mine exactly like you said and it works great. I moved mine to the wall because I only have a 2x2 closet. My leaf offset is 5 degrees.

2 Likes

Your experience is the same as mine: generally 5-6° lower leaf temp than ambient. Since VPD is calculated for our purposes to maximize open stomata and photosynthesis, the leaf temp is what is most important. I aim to hang my sensor under the light and an inch or two above the middle of the canopy.

1 Like

One other thing I’ve found is depending on the intensity of the light source, the difference between leaf and ambient temperatures can change. For example, early on with seedlings my offset is closer to -2°. As the light intensity ramps up over the course of the grow, so does the difference between ambient and leaf temperatures.

1 Like

I agree. Also I have fans blowing across the top of the canopy to help with temperature between light and canopy. I appreciate your input. :+1:t2: Helping each other is where it’s at. :star_struck::sunglasses:

1 Like