Can lights be used to grow plants?



  1. 0 Votes

    The answer is YES; most definitely.The ability for us to use artificial lighting to make sure the plants are engaged in photosynthesis is very useful for the winter time or places where they would otherwise not get enough sunlight. I will summarize what is important and then give you suggestions at the end.

    There are a few factors involves. First, it is important that you providing the right kind of light. Plants absorb the most chlorophyll at ranges of 610 – 720 (right before IR) but also in the 400-520 (right after UV). [ look up  —  Chlorophyll ab spectra2.PNG — on google ] It is crucial that you get a bulb that provides light in the right wavelength or the spectrum to get the most chlorophyll absorption.

    Next, many bulbs will produce too much heat, which can damage the plant, so either keep the bulb farther away from the plant or invest in bulbs that do not get very hot and are specifically for growing plants.

    Also, plants will need 12-18 hours of artificial lighting or combination of artificial and natural lighting (time varies depending on plant) and I would suggest using a timer for this. This is also important when we look at the lifetime of the bulbs. For something that is on for at least 80 hours a week, you want something efficient and something that will last.


    Incandescent lights can get very hot and last about 750 hours.

    There is a line of fluorescent lights called T5, T8, T10 and T12, They range in intensities, heat and life spans, but do not produce a lot of heat and can last up to 25 times more (20000 hours) than incandescent lights.

    Metal Halides(MH) are very good because they mimic the natural white sunlight well (~80%) and also last up to 25 times longer than incandescent, depending on the wattage. They produce a blue light.

    High Pressure Sodium (HPS) lights are good for greenhouses and are very effective compared to incandescent light, in terms of life span and light output per watt. The problem is that it mainly gives off light in the red/orange spectra, so the plants tend to look pale, but grow to be lanky and tall.

    A combination MH and HPS is said to yield very good results because you will be getting both sides of the light spectrum. They also sell convertables/switch bulbs, where depending on stage of growth, either the MH or HPS is on, but not at the same time. This is also said to be very effective because growing and fruiting require specific and different wavelength to be most efficient.

    LEDS would seem like a good light source, considering their long lifetime, great wattage and output and low heat, but there have been some debates about their efficiency over time, Claims are that they do heat up and their life time is severely truncated. I would not suggest LEDs.

    I believe you will find the sites that I am using as citations very helpful.

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