> For the complete documentation index, see [llms.txt](https://faq.growsensor.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://faq.growsensor.co/welcome/what-does-the-grow-sensor-measure.md).

# What does the Grow Sensor measure?

Here’s what it measures and why it matters:

* [Temperature](https://www.growsensor.co/post/ideal-temp-humidity-grow-tent-part-1) – Controls plant metabolism, affecting growth speed and nutrient uptake. Too hot or too cold can stress plants and reduce yields.
* [Relative humidity (RH)](https://www.growsensor.co/post/ideal-grow-room-temp-humidity-part-2) – Impacts transpiration and nutrient absorption. High RH can lead to mould, while low RH can slow growth.
* [CO₂ levels ](https://www.growsensor.co/post/maximize-your-cannabis-yield-the-essential-guide-to-co2-supplementation-for-home-growers)– Essential for photosynthesis. Maintaining ideal CO₂ levels boosts growth and maximises yields.
* [ePPFD](https://www.growsensor.co/post/ultimate-ppfd-meter) (extended Photosynthetic Photon Flux Density) – Monitors how much light plants receive, ensuring the right amount of light for optimal photosynthesis.
* [ePAR](https://www.growsensor.co/post/apogee-par-meter-vs-grow-sensor-a-comparison) (extended Light Spectrum) – Monitors the full range of light wavelengths plants use for growth, improving energy efficiency and development.
* [eDLI](https://www.growsensor.co/post/ppf-dli-the-grow-sensor) (extended Daily Light Integral) – Tracks total light exposure over 24 hours, helping to optimise lighting schedules.
* [Leaf surface temperature](https://www.growsensor.co/post/why-leaf-surface-temperature-important) – More accurate than ambient temperature for detecting heat stress and optimising VPD.
* Ambient VPD ([Vapour Pressure Deficit](https://www.growsensor.co/category/vpd))– Helps balance humidity and temperature for stress-free plant growth.
* [True Leaf VPD](https://www.growsensor.co/post/measuring-leaf-surface-temperature-with-the-grow-sensor) – Ensures efficient transpiration, preventing overwatering and nutrient lockout.
* Leaf temperature off set. - Shows you the live difference between ambient temperature and leaf temperature. 
* Substrate EC (Electrical Conductivity) – Indicates nutrient concentration in the growing medium, preventing over- or underfeeding.
* Water content in the substrate – Prevents over- or underwatering, improving root health.
* Root zone temperature – Affects nutrient absorption and root development.
* [Dew point](https://www.growsensor.co/post/dew-point-cannabis-growers) – Predicts condensation risk, reducing the chance of mould and mildew.
* Air pressure – Can impact gas exchange and overall plant health.

With the Grow Sensor, you get precise data to fine-tune your environment, reduce risks, and maximise yields effortlessly.


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