Light intensity is the amount of light measured over a certain area. In essence, it is how much light is being provided. The lighting industry measures light intensity in lumens; however, we know lumens are for humans and not for plants. In horticulture, light intensity is measured in micromoles (μmol) which describe the amount of photons emitted from a light source. Those photons are what plants perceive.
There are a few different ways to measure umols from a light source:
- Integrating Sphere Spectroradiometer
- Light Meter