The Grow Light Checklist

Not everyone has a green thumb, but when business demands reliable plant production, that’s not an acceptable excuse. Thankfully, science and engineering can eliminate guesswork in your growing. Growlights are among the most important tools in your arsenal, and they can be the key to consistent, year-round growth. This checklist will cover the three components of lights you need to understand to pick the right technology for your plants.


Typically, a manufacturer provides a lumen rating for any given light. This literally describes how much light is produced by the device, and it can help in selection, but it is not the best measure. Light intensity is better measured in lux. This is a number that will tell you how much light passes through a cross section at a distance. Not all manufacturers provide a lux rating, but there is an easy trick to gauge this value.

Simply divide the luminosity (lumens) by the area of plants receiving the light to see what the intensity value will be. This tells you how thinly you can distribute your grow lights before they lose effectiveness.


The color temperature of light is just as important as the brightness or intensity. No two plants thrive under the exact same color temperature, and many plants even change their preferred temperature during different cycles.

Color temperature is measured in Kelvin, and this is a literal temperature measurement. It demonstrates the radiant temperature of the reflected light. When searching for the right color temperature, the simple reminder is that visible light mostly ranges from 2500 to 7500K. The lower number will indicate a red color, and the higher numbers move across the rainbow into the blue end of the spectrum.

Light Production

The last item on the checklist compares what object is producing the light. There are plenty of different ways to make a light, and in greenhouses, the most common are LED, fluorescent and incandescent lights. In the early days of LED production, there was a fair trade-off between these different technologies. Today, LEDs are superior in almost every setting.

LED lights cost less to make, use less energy, produce less heat, last longer and provide more control over lighting. Very few applications are better served by fluorescent or incandescent lights, so stick to LEDs as much as possible.

Grow lights are pretty simple. Manufacturers provide plenty of hard numbers to help you understand exactly what you are getting. When you match the numbers to what your plants need, you’ll have optimal lighting and excellent results.