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Why Are Grow Lights Purple – Top 5 Reasons Behind

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Are you a newbie grower? Starting your journey as a plant parent comes with new experiences and so many questions. Or are you just on the quest to know as much as you can about your plants?

For most growers, the gain of knowledge in their journey is just as much of a highlight as the journey itself. Have you recently bought grow lights and have been wondering why are grow lights purple?

The path as a grower is one with countless new experiences and questions. There never seems to be an end to what you can learn about your plants and other people’s journeys. If you’ve recently found yourself wondering why are grow lights purple, keep reading cause we’ll be telling you all about it.

Why Are Grow Lights Purple
Echeveria inside for the winter under Grow Lights. No color editing. – via Flickr

What Are Grow Lights?

Grow lights are electric lights that help plants grow. They either try to provide the plant with a light spectrum that is similar to that of the sun or change the spectrum to one that is even more beneficial for the plant than the sun. They mimic outdoor conditions by varying color, temperature, and light spectrum.

What Are Purple Grow Lights?

Red and blue light spectrums are used the most in the development and growth of indoor plants. Purple light is the combination of these essential red and blue spectra. This combination is even more fruitful and beneficial for the plants than just the red and blue spectrum alone.

Benefits Of Grow Lights

Quick Cycle Of Harvesting

When you’re using grow lights, you’ll observe that plants grow faster even when they are under shade. This means the harvest cycle is reduced.

Spectrum Accuracy

The wavelengths and spectrums used in LEDs allow the grower to spike different reactions from their plants by varying them, like growing new leaves, etc.


Grow lights are eco-friendly not only because they can be reused, but also because they don’t contain harmful substances that can harm your plants.

Less Heat Emission

The heat in grow lights can be controlled according to your plant’s preference. Direct sunlight can burn the plants due to too much heat but with grow lights, you can adjust the amount of heat without changing the wavelength.


The feature of being able to control the amount of heat means that you can lower the amount and increase the proximity between the light source and the plant.


Grow lights come in a wide range of shapes, sizes, and prices. So, you can choose the grow light that is best suited for your budget and plant requirements.

Why Are Grow Lights Purple 2
Led grown lights useful – via Wikimedia

Why Are Grow Lights Purple?


Grow lights consists of diodes that emit light of a specific color. Purple grow lights consist of red and blue diodes, which are the most essential spectrums for the plants.

There are around five times more red diodes in comparison to blue ones and the amount of these is way more than diodes of any other color.


Producing red and blue diodes and light spectrum is easier and cheaper. This is the major reason for the color of grow lights, no matter what else is claimed.

When the production is cheaper, the final cost of the light that is to be paid will also be less, leading to an increase in the use and sales of purple grow lights.

Photosynthetic Activities

The violet hue of the grow light actually promotes photosynthesis. Purple light is the most important for photosynthesis because it contains the wavelengths that supply the plant with the most energy.

Energy Efficient

The low cost is promoted even more in purple grow lights. You can use the lights for less time and still have better results and good-looking plants. They are energy efficient and reduce the cost of electricity bills for the growers. What can be better! You can even save up to get a new plant!


Purple LED grow lights also prevent tent fires as they have less heat output. Grow lights that release more heat need to be used with caution, especially when placed in a growing tent or indoors. This safety is an added benefit of these grow lights.

Why Are Purple Grow Lights Uncomfortable For Humans?

CRI or Color Rendering Index is what concludes a standard for how comfortable or pleasant a light is to human eyes. To simplify this, CRI is basically a measure of how natural light makes an object under it look. Purple grow lights have a very low CRI as all the objects placed under them will look purple. Even though this isn’t harmful to human eyes, it can be quite uncomfortable.

Purple Grow Lights vs White Grow Lights


Purple grow lights are way cheaper in comparison to white grow lights. The cost to produce them is lower because of which the prices in stores are also lower. This is a huge reason for their regular use in many plant households.

White grow lights are more expensive which is why they are less likely to be found in a grower’s home.


Purple light has the highest efficacy compared to all others. This means that its conversion of electricity into photons is the highest.

Comfort For Humans

Purple light doesn’t provide the best work environment for humans to work in. It isn’t harmful but can be a nuisance that slows down work.

The plants don’t look green under the purple light so it’s difficult to pick out if anything is a miss. This isn’t the case with white light, under which everything is perfectly visible.


In this article, we discussed all the reasons why are grow lights purple. Even though some aren’t, many people prefer theirs to be purple because of all the different benefits (especially the price!).

This basic introduction to grow lights will not only satisfy your curiosity but will also help you understand your plant’s needs and requirements.

Hopefully, this helped you understand why are grow lights purple and further helps you in choosing a grow light for your own plants!