How Do Different Light Sources Affect Plant Growth?
Sunlight is the most natural source of light for healthy plant growth. As a result, plants grown indoors may not receive the needed amounts and quality of light needed for healthy growth. Artificial light sources vary in the amount heat they give off and the types of colors they contain, which can affect the overall health of the plant. Does this Spark an idea?
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Function
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Light is one of the most essential things used by plants to manufacture food for growth, according to the University of Missouri Extension. They do that by converting light energy into chemical materials, and they are the only organisms capable of carrying out that process. Sunlight contains a certain balance of colors, including blue, red, green and yellow. Indoor plants that get insufficient, full-spectrum light may be unable to manufacture the materials needed for growth; however, some artificial light sources can replace needed color requirements.
Light Effects
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Plants naturally absorb certain colors from light, and reflect others. As a result, plant leaves appear green or yellow because those are the colors being reflected and not absorbed. It's the blue and red light waves that most nourish and support plant health and growth, according to the University of Missouri Extension. Once absorbed, plants go through a photosynthesis process that uses the energy from the light to break down carbon monoxide and water molecules into carbohydrates. In effect, different light sources determine how efficiently a plant is able to produce food.
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Colors
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The quality of light a plant gets depends on which colors and how much of each is in the light, according to the Oregon State University Extension. Each color has a different wavelength, which is the amount of energy it contains. Blue wavelengths work to promote leaf growth in plants, while red wavelengths promote flowering. Optimal light sources contain a combination of blue and red wavelengths, with a little more red than blue. When using an artificial source, color quality can vary between fluorescent and incandescent light.
Incandescent vs. Fluorescent
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Incandescent and fluorescent are the two primary types of artificial lighting sources. While incandescent sources can be convenient and less costly, their heat output is a bit more than plants can handle, according to the University of Missouri Extension. Incandescent lights do contain a good amount of red color waves, but not enough blue.
Fluorescent light sources, or cool white light, contains a good amount of blue wavelengths. Warm-white fluorescent bulbs are also made to contain adequate amounts of red wavelengths as well. And while they may be more costly, fluorescents are highly efficient in converting electrical energy into light, meaning they give off less heat in the process.
Light Balance
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Plant needs may determine what balance of red and blue wavelengths will best promote growth, according to the University of Missouri Extension. Starter plants may require more blue light, whereas leaf growth and flowering needs in mature plants are best met by red wavelengths. When using both incandescent and fluorescent sources, a 3 to 10 ratio can provide optimal lighting conditions for mature plants. This ratio uses 100 watts of fluorescent light for every 30 watts of incandescent, which contains the needed balance of red and blue wavelengths.
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