We all know that plants need light to thrive. In fact, light is the energy source for plant life on Earth. You may also know that plants rely on light to be nourished through a self-sustaining process called photosynthesis. Additionally, the chlorophyll in plants relies on visible light to convert available carbon dioxide into energy.
Light and plants go together like peanut butter and jelly. You truly can’t have one without the other. However, we don’t always think about the way that color impacts plants.
So does the color of light affect plant growth? Once you understand the science, you can actually use wavelengths to manipulate how plants grow.
According to researchers at UC Santa Barbara, “Different colors of light have different energy levels.” Blue light, red light, green light and other colors all impact plants differently. The interesting twist is that green light actually isn’t the most beneficial light color for plants, even though plants are green. We can let science explain the reason for that. When looking at an object, the color that our eyes perceive is actually the color that’s being reflected back at us. When we look at a plant, the color we see is green. That means that plants aren’t truly absorbing green wavelengths.
Many growers wonder if they can “hack” the color situation inside their greenhouses or grow areas to produce better yields. The answer is that calculated exposure to specific light colors can actually produce fuller, healthier plants with higher yields. Many large-scale growers now utilize light systems with very specific wavelengths to foster specific characteristics and qualities in plants. This often includes texture, height and color.
How Colors Impact Plant Growth
Take a look at how the different colors of light impact plants.
Violet is really the “taste” color for plants. As a shorter wavelength with intense energy, violet is especially useful for promoting the growth and development of a plant’s leafy parts. In general, violet exposure produces richer colors, tastes and aromas in plants. It’s an important color for helping fruits and vegetables to become the tastiest, juiciest specimens they can be. Violet is also thought to protect plant health.
While plants absorb many colors, only green is reflected by plants. Green light also enhances chlorophyll production. It’s also important for plant pigment. Green light’s ability to produce greener plants makes it very useful in commercial greenhouses where visual appeal is so important.
Considered essential for growth, blue light can help to ramp up growth potential very early on in the growing process. Blue light given in the germination phase is linked with much stronger plants. Exposing plants to high blue-light concentration is linked with stronger roots and robust sprouting. Overall, growers are fond of blue light for helping plants to reach maturity faster. A big reason for the fortifying benefits of blue light is that it is an easily absorbed light that allows plants to take in more “fuel” for growth through photosynthesis.
Red light is associated with better blooming. However, many growers have mixed results when using just red. While plants may bloom larger when exposed to red light, they also sometimes become too thin and weak under the weight of the “expanded” bloom. While red may rev up appetites and impulsivity in humans, it’s simply not a major powerhouse for plants unless it’s paired with other colors. Researchers have found that balancing red light with between 10 percent and 20 percent blue light creates much bigger and healthier blooms.
A variant of red light called far-red light is also important for plants. Far-red light is interesting because its ultra-low wavelengths are actually comparable to infrared wavelengths. According to researchers, exposure to far-red light actually increases plant yield significantly by supercharging the replenishment process that plants go through at night.
Yellow light essentially has a neutral impact on plants. Most researchers compare the impact that yellow has on plants to the impact that green has on plants. However, yellow does not offer the same chlorophyll-related benefits.
Unlocking a Plant’s Potential With Color: Is This Something You Should Try at Home?
Commercial growers almost universally purchase high-tech lighting systems that deliver the precise wavelengths needed for optimal growth at various times of the growth cycle. However, even amateur growers with backyard greenhouses or window boxes can try some lighting techniques.
Certain lights are better than others if you’re an at-home grower. Take a look:
- High-Intensity Discharge Lights: These may be out of your league if you’re looking for a small-scale system. Used primarily by commercial growers, high-intensity bulbs produce lots of heat by using up lots of energy. They’re the top pick if you’re very serious about investing in your greenhouse. High-intensity lights should be placed 5 feet to 8 feet from plants.
- Fluorescent Lights: Rich with blue light, fluorescents are ideal when growing leafy greens and herbs. They are also energy-efficient lights that don’t produce tons of heat. Fluorescents provide the most benefit when placed 4 inches to 6 inches from plants.
- LED Lights: Considered the best pick for hobbyists, LED is good for small-scale greenhouses that can benefit from red and blue light. LEDs work best when placed between 14 inches and 30 inches away from plants.
Save your time and money by skipping incandescent lights completely. While they are often sold as grow lights, incandescent lights are too weak to really benefit plants. Many newer growers are fooled into the believing that the rich glow produced by incandescent lights is actually doing something.