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Purple Grow Lights

Purple grow lights: Why do most LED lights appear purple?

Why do cannabis gardeners use purple LED grow lights when they cultivate marijuana indoors?

Is there an advantage of using violet instead of other colored lights?

As we answer these questions and show you how to optimize the use of purple LED grow lights in your indoor grow space, you’ll be able to utilize the knowledge to produce a robust crop and harvest quality buds.

How LED grow panels and bulbs often produce purple light

Research has shown that marijuana grow lights with blue and red spectra play essential roles in your plant’s growth and development. 

That’s why manufacturers combine red and blue diodes to create purple grow lights. You’ll need to use one instead of many bulbs.

Next, we’ll explain the different wavelengths that make up the violet light and why synthesizing them benefits your plant.

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LED light wavelengths

When you look at purple LED grow lights, the color is the result of combining different wavelengths. The red and blue ones merge to give you the violet hue.

Every wavelength comes in a range that’s measured in nanometers or “nm.” Here are several examples:

  • Blue light: 450–495 nm.
  • Red light: 620–750 nm.
  • Ultraviolet: 100–450 nm. Two of the standard UV lights for growing weeds are UV-A and UV-B.
  • Infrared: 700–1050 nm.

Now, let’s look at the blue and red wavelengths individually.

Blue light wavelengths 

The blue wavelength in purple grow lights is essential if you want healthy cannabis plants. It influences photosynthesis, chlorophyll production, leaf expansion, nutrient uptake, and overall plant growth. 

When you expose your plant to blue light, it’s likely to grow shorter and thicker, with smaller stems. It’ll also produce larger and darker green leaves than plants that don’t get sufficient blue light.

Red light wavelengths

In the light spectrum for growing weed, red lights benefit marijuana plants by stimulating seed germination, root growth and increasing your plant’s photosynthesis rate. The result is taller plants with longer stems.

The reddish hue in purple LED grow lights is also essential for your plant’s flowering and fruiting processes

Blue and red light wavelengths combined

Many studies have shown the effects of red and blue light on weed plant development. It’s why cultivators use violet light bulbs that have a mixture of both hues.

Although plants benefit from both red and blue hues, they typically need more of the former. So, you’ll need to ensure you choose grow lights with a suitable ratio in each stage of your plant’s development.

Why do LED grow lights use mainly red and blue diodes?

When looking for the best LED grow lights, you’ll notice that most of them use blue and red diodes in purple LED bulbs. That’s because plants need those colors during photosynthesis

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Research shows that plants use five times more red than blue or any other color. Individually, the former affects fruiting and blooming, while the latter stimulates growth. 

So, when you combine the two hues in purple grow lights in the right proportion, your plant will get the light it needs to thrive.

Typically, the red-blue ratio that offers the widest benefit for most plants is 80–85% red and 15–20% blue

Are purple LED grow lights effective?

Purple LED grow lights combine blue and red wavelengths in the optimal ratios to provide your plant with what it needs to thrive. 

These violet lights are effective because you focus only on the light your cannabis crops need and use.

However, when choosing the light spectrum for growing weed, you’ll have to consider the wavelength ratio because the vegetative stage requires more blue. Red is essential during the flowering phase

To get taller plants, go for a deeper violet light as your weed needs more blue wavelengths. Use a grow light with more red for thick leaves and bigger buds.

Pros of purple light

The key advantage of using purple light for plants is that it comprises the blue and red wavelengths your cannabis needs to thrive.

You’ll also save on lighting costs as you only need to use one colored grow light instead of individual blue and red lights.

Cons of purple light

While it’s still accepted that purple LED bulbs benefit your plant’s development, researchers suggest that red and blue light frequencies may not be the only ones vital to your crop’s health.

The idea is based on the fact that plants flourish in sunlight, which contains all colors of the spectrum.

When should purple grow lights be used?

Purple LED grow lights can be used throughout the light cycle for weed. However, you’ll need to vary the blue-red ratio during the vegetative and flowering stages.

You should use a bulb with more blue wavelengths when your plant is in its growth phase and one with more red when it’s time to flower.

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How do you get the ideal color spectrum?

Studies have shown that red and blue light frequencies offer the greatest benefit to plant growth and development in the light spectrum for growing weed. 

However, experts say that the best spectrum should comprise all hues—but have more red and blue than the others. The average proportion of red to blue should be 85:15.

Since UV lights for growing weed and an infrared grow light will improve your yield, combining all the colors with UV and IR would produce the ideal spectrum.

FAQ related to purple grow lights 

In this frequently asked questions section, we’ll offer further insights that’ll help you learn more about purple grow lights.

Feel free to get in touch with us if you need more information.

Can any LED light be used as a grow light?

To an extent, any LED light can be used as a grow light. However, as your plant uses more red and blue wavelengths for its growth, the other colors won’t be used effectively. 

It’s why you use purple LED grow lights. They offer what your plant needs.

Why is my grow light purple? 

Violet LED bulbs consist of blue and red diodes, and the mixture of these two hues gives you purple grow lights. These bulbs provide your plant the wavelengths it needs for growth and flowering.

Does a grow light have to be purple? 

Ideally, your herb will benefit from white, UV, and infrared lights. However, using all of these bulbs is expensive—that’s why many cultivators prefer to use purple light for plants since it contains the red and blue frequencies crops need for optimum growth.

Is purple light healthy for my plants?

Blue light is essential for your weed’s growth, and red is vital during the flowering stage. Since violet LED lights combine the two colors, it’s healthy for your plant’s development. 

What color light is best for flowering? 

Besides determining how much light does a weed plant need, the LED light spectrum for plants you use during each growth stage is also critical. When your plant is flowering, you should add more red light to increase the quantity and quality of your buds.

Purple grow lights are key to healthy cannabis plants

Now that you understand how colors influence your plant’s growth and why red and blue hues are the most essential, you’ll be able to put purple grow lights to optimal use and produce beautiful cannabis plants with amazing buds. To learn more and get other growing tips, check out our blog.

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