What Color Light Would Be The Best For Growing Plants In A Greenhouse

If you’re asking what color light would be the best for growing plants in a greenhouse, the answer is blue and red. However, it’s worth emphasizing that plants will grow well with most colors of lights, and the amount of each color will be the deciding factor. Blue and red are the best color light for growing in the greenhouse because they are close to the spectra that plants use.

Additionally, plants can also use some green and yellow. The gardener needs to ensure the proper color of grow light in the greenhouse beside the other conditions like temperatures. After all, the control you have on the greenhouse conditions is its primary advantage, regardless of location and weather. 

What Color Light Would Be The Best For Growing Plants In A Greenhouse

How To Choose What Color Light Would Be The Best For Growing Plants In A Greenhouse

When choosing a color of grow light, it’s a common mistake to choose green, yellow, and orange because we’re assuming they are similar to the spectrum given by the sun. After all, we’re mimicking the conditions that plants require for growth, right? However, studies show that photosynthetic activity of plants is in the blue and red frequencies. 

For growing plants in the greenhouse, it will be best to use red and blue lights because they take in maximum chlorophyll as a response in these colors. However, you must understand that there are different types of lights and colors that you can use in the greenhouse. While blue and red are the best colors for growing plants, a full spectrum LED grow light will be ideal for the greenhouse. 


Fluorescent lights vs. LED lights

If you use a fluorescent bulb that emits blue lights, this will help to get bushy plants. Fluorescent bulbs are also excellent when seeding because they don’t give off too much heat. It’s worth noting that when choosing a fluorescent lamp, you may choose between cool white and warm white, where the former has more blue. 

On the contrary, the more energy-efficient and long-lasting LED lights use wavelengths. This makes it easier for you to choose the actual color spectrum as opposed to fluorescent bulbs. Keeping this in mind, the following information will discuss each color and its effects on plants.  


Blue light

Before you use blue light, the emphasis is necessary on mixing it with other spectra of lamps. This color affects the leaf thickness and color, energy acceptance, and chlorophyll content, but some plant species can experience stunts in growth from this color. A minimum intensity of blue light is enough to help with growth and maturity rate and minimize plants’ water loss. 


Red light

Another influential color of light for growing plants in a greenhouse is red. This spectrum is best to combine with blue if you genuinely want to achieve well-developed plants. This is because this wavelength plays a role in the germination of seeds, flowering, and expansion of leaves and stems. 


Green light

Among the spectrum of colors, gardeners usually ignore the green light because it has the least efficiency. But according to Michigan State University, it is still useful in photosynthesis and plant structure. A green light is also helpful for the greenhouse with thick top canopies so that the lower canopy leaves still receive light.


What Is DLI?

When looking for the color of grow lights, you might encounter the term DLI. This term gives you an idea of how much light will be available to the plant to use for photosynthesis. Therefore, more DLI means more photosynthesis, equals better growth. 

In greenhouses, adding grow lights to increase the DLI will help produce quality plants. The rate of growth will depend on the productivity of the plants. However, you must also know the proper distance between the plants and your light. 

Remember that you might use fluorescent, LED, or high-intensity discharge lights depending on your greenhouse operation. If you’re using LED lights, maintain a distance of up to 30 inches above your plants. On the contrary, fluorescent lights can have a space of 6 inches above the plants, while high-intensity discharge lights can be 8 feet above the plants. 


Is Light Intensity Important For Growing Plants In A Greenhouse?

After learning the color spectra, the next step is to realize the importance of light intensity in the greenhouse. In general, the higher the intensity, the higher the rate of photosynthesis will be as well. As discussed previously, the addition of grow lights is vital because greenhouse glazing decreases the light available for photosynthesis. 



Maintaining optimum conditions in the greenhouse can be challenging. Besides the proper temperatures, do you know what color light would be the best for growing plants in a greenhouse? The direct answer would be a combination of blue and red lights because these colors are the most significant for plant growth. 

Studies have shown that these colors are close to the spectra that plants use. But while these are the best colors, a full range LED grow light will be the most beneficial for your plants. Each color has a role for the plant’s health, so learn the amount your plants will need for each color instead. 


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