Grow lights come in a variety of shapes, sizes, and spectrums. Recently, full spectrum led grow light, particularly those that claim to provide the full spectrum of light, have become popular. Before you take the plunge and purchase full spectrum light, you may be wondering if it’s worth the hype and, given that LEDs tend to be among the more expensive lighting options, the price.
LED lights have been around for a while now, and most people are familiar with them as a more efficient, longer-lasting alternative to incandescent or compact fluorescent lights. LED stands for light-emitting diode, and the main difference between an LED light and other lights is that they emit light in a single direction. Directed light emission means they can use energy more efficiently rather than losing it to the surrounding environment. They also do not contain mercury like many other lights. Using LED lights is both environmentally friendly and better for your power bill.
A powerful led grow light claims to produce light resembling sunlight, and to humans, it does. That’s what a bullet point on a product page referring to a color-rendering index (CRI) of 90 or higher means. The highest possible CRI is 100, which is the same as a standardized level of daylight.

Full-spectrum LED lights are popular in homes and offices for just that reason: to us, colors appear the way they should when lit by an LED light. The spectrum being referred to when a product claims to provide the highest yielding led grow light generally means the light we can see from red to violet, like in a rainbow, along with infra-red light.
While it all sounds very scientific, "full-spectrum" is a marketing term. From a scientific perspective, the full electromagnetic spectrum ranges from gamma rays produced by radioactive particles to radio waves, which, while not harmful, aren't useful to plants either. This can be confusing because both the full range of electromagnetic radiation and visible light are referred to as a spectrum. It's easiest to think about them in terms of their wavelengths. The full electromagnetic spectrum encompasses wavelengths between one billionth of a nanometer and one hundred kilometers. As discussed in the next section, plants only use wavelengths between 400 and 700 nanometers, roughly the same as what human beings can see, making it the "full-spectrum" of visible light. In this article, the spectrum being discussed is just visible light.