# What is leaf VPD, and can I see this in the graphs?

Leaf VPD is a key indicator of plant health, helping you optimise your grow environment for better yields.

Leaf VPD (Vapour Pressure Deficit) measures the difference between moisture inside the leaf and the surrounding air. This directly affects:

* **Transpiration efficiency** – How well the plant releases moisture.
* **Nutrient uptake** – Ensuring plants absorb what they need.
* **Growth rate & health** – Maintaining the ideal humidity-to-temperature balance.

You’ll find Leaf VPD as a dedicated graph in your Grow App, giving you real-time insights into your plants’ transpiration and overall health.

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