The correct VPD helps plants grow their best. To accurately track the VPD that plants feel, you need to know the temperature at the leaf. Pulse can take that "leaf VPD" into account when displaying VPD in the app to guide you to better results.

What you'll need to get started

  1. IR thermometer gun
  2. Notepad
  3. Pulse App
  4. Calculator

 

Calculating the VPD leaf temperature offset

  1. Make sure lights are on and have been for a good amount of time ( > 1 hr)
  2. Get your IR thermometer gun
  3. Collect 4-6 temperature readings of leaves in the canopy at various different spots: top, bottom, middle, sides, etc. Write these down.
  4. Collect 4-6 temperature readings of non-plant material: supports, walls, pots, plastic, wood, etc. Write these down.
  5. Get the average of the canopy temperatures.
  6. Get the average of the non-plant temperatures. 
  7. Subtract non-plant temperatures from canopy temperatures: (T Canopy) - (T Other) = Leaf Temperature Offset
    • Ex: Canopy average temps 75, other average temps 80
      • 75 - 80 = -5
    • Ex: Canopy average temps, 65, other average temps 60
      • 65 - 60 = 5
  8. Enter the leaf temperature offset into the app.
    1. Log in > go to the dashboard > tap / click on a device > tap / click on the gear icon in the top right > scroll down until you see a section called "VPD Leaf Temperature Offset"
    2. Enter the offset you calculated in step 7, make sure to mind the negative sign if there is one.
    3. Tap / click the blue update button.

 

FAQ

  • How often should I do this?
    • Once a month is sufficient.
  • Why don't you have a separate VPD leaf temperature offset for night?
    • VPD doesn't matter at night since plants close their stomata. 
  • Where should I measure the leaves?
    • All across the canopy - left to right, top to bottom.