The optimal duration of blue light exposure for plants depends on the type of plant, the stage of growth, and the desired outcome. Generally, blue light should be provided for at least 6 to 8 hours per day, but not more than 18 hours.
Blue light is a vital component of the light spectrum that plants use for photosynthesis, growth, and development. Blue light has different effects on plants than other colors of light, such as red or green. In this article, we will explore how blue light affects plants, how to use blue light for indoor gardening, and what are the best sources of blue light for plants.
Blue light is usually referred to as radiation with wavelengths between 400 and 500 nm. This waveband is within the visible spectrum, has relatively high energy, and has pronounced effects on plant growth and flowering.
Blue light interacts with the leaves in such a way that the stomata on the tips of the leaves open up and let in more carbon dioxide. More carbon dioxide is essentially more fuel for the plant to grow. Carbon dioxide along with water and nutrients from the soil all play an essential role in the photosynthetic process.
Blue light also regulates the opening of stomata, which are the tiny openings on leaves that control both water loss and the uptake of carbon dioxide. Generally, only a low intensity of blue is needed in a light spectrum for fully functional photosynthesis.
Blue light is a strong regulator of plant height and flowering. Generally, blue light makes plants more compact by making stems shorter and thicker. In long-day plants, like Cannabis, blue light can promote flowering. In the production of ornamentals, these attributes can be desirable because in essence, blue light can act as a growth regulator.
Radiation with shorter wavelengths (blue/UV) stimulates the production of compounds that can influence leaf coloration. For example, in the absence of blue/UV radiation, plants that have purplish leaves outdoors may have green leaves. In some leafy greens crops such as lettuce, blue/UV also increases the production of healthful compounds such as antioxidants and some vitamins. Thus for these crops, delivery of blue/UV radiation prior to marketing can increase crop quality attributes such as leaf coloration and nutrition.
How to Use Blue Light for Indoor Gardening
While outdoor plants in full sun will naturally receive both red and blue light, indoor plants might be lacking in it. Even plants next to a window may not be receiving enough of a certain part of the color spectrum. If your plant is getting leggy or losing the green color in its leaves, odds are it’s not getting enough blue light. If it’s not flowering at a time you know it should, it’s probably lacking in red light.
You can supplement blue light with fluorescent lamps. While using red light for plants is possible with incandescent bulbs, these often produce too much heat to be kept near houseplants. Use a broad spectrum fluorescent bulb instead.
The optimal duration of blue light exposure for plants depends on the type of plant, the stage of growth, and the desired outcome. Generally, blue light should be provided for at least 6 to 8 hours per day, but not more than 18 hours. Too much blue light can cause stress and damage to the plants, especially if the intensity is too high.
The best way to use blue light for indoor gardening is to combine it with other colors of light, such as red, green, or white. Different colors of light have different effects on plants, and a balanced spectrum can provide the best results. For example, red light can enhance flowering and fruiting, green light can penetrate deeper into the canopy and improve photosynthesis, and white light can provide a natural appearance and improve plant health.
Best Sources of Blue Light for Plants
There are many types of artificial lights that can provide blue light for plants, such as fluorescent tubes, compact fluorescent lamps (CFLs), light-emitting diodes (LEDs), metal halide lamps (MHs), and high-pressure sodium lamps (HPSs). Each type of light has its own advantages and disadvantages, such as cost, efficiency, lifespan, and spectrum.
Fluorescent tubes are the most common and affordable source of blue light for plants. They are easy to install and operate, and they have a low heat output. However, they also have a low light intensity and a limited spectrum. They are best suited for low-light plants or seedlings.
CFLs are similar to fluorescent tubes, but they are more compact and energy-efficient. They can fit into standard sockets and provide a wider spectrum of light. However, they also have a low light intensity and a short lifespan. They are best suited for small spaces or supplemental lighting.
LEDs are the most advanced and versatile source of blue light for plants. They are very energy-efficient, long-lasting, and customizable. They can produce a specific spectrum of light, such as blue, red, or full-spectrum. They also have a high light intensity and a low heat output. However, they are also the most expensive and complex to use. They are best suited for high-light plants or large-scale operations.
MHs are a type of high-intensity discharge (HID) lamp that produces a bright and cool white light. They have a high light intensity and a broad spectrum of light, including blue and UV. However, they also have a high heat output and a high energy consumption. They require a special ballast and a reflector to operate. They are best suited for vegetative growth or flowering plants.
HPSs are another type of HID lamp that produces a bright and warm yellow light. They have a high light intensity and a narrow spectrum of light, mainly red and orange. However, they also have a high heat output and a high energy consumption. They require a special ballast and a reflector to operate. They are best suited for flowering and fruiting plants.
Conclusion
Blue light is an important factor for plant growth and development. It affects photosynthesis, stomatal opening, plant height, flowering, leaf color, and nutrition. Blue light can be supplemented with artificial lights, such as fluorescent, LED, or HID lamps. The optimal duration of blue light exposure for plants depends on the type of plant, the stage of growth, and the desired outcome. Generally, blue light should be provided for at least 6 to 8 hours per day, but not more than 18 hours. Blue light should also be balanced with other colors of light, such as red, green, or white, to provide the best results for indoor gardening.
