What Is a Plant Grow Light Bulb?


A plant grow light bulb is used to provide light to indoor plants. It supplies the equivalent of sunlight, allowing plants to thrive and grow as they would outside.

Three Kinds of Lights

There are three kinds of plant grow light bulbs: High Intensity Discharge (HID) bulbs, fluorescent bulbs and incandescent bulbs.

High Intensity Discharge (HID) Grow Lights

High Intensity Discharge lights come in two forms: metal halide, which is used to encourage leafy growth, and high pressure sodium, which is used to encourage flowering and budding in plants.

Fluorescent Bulbs

Recent changes in technology have made fluorescent grow lights more viable than in the past. They are now an energy-efficient option for an indoor plant grower and produce less heat than other lighting.

Incandescent Bulbs

Incandescent bulbs are generally not used for indoor plant growing due to their inefficiency and low light output.

Different Parts of the Spectrum

High pressure sodium lights produce light in the yellow and red regions of the spectrum, while metal halide lights produce light lower down in the blue region.


  • LittleGreenhouse.com: Indoor Plant Grow Light Guide

Who Can Help

  • 4hydroponics.com: Grow Light Bulb Tutorial
Keywords: grow light, growing plants, light bulb, indoor growing
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