Effects of Red and Blue Light on Plants
What we perceive as white light from the sun is actually made up of all the colors of the rainbow. The three major colors of light are red, blue, and green. We can tell that plants don’t absorb much green light because it reflects off of them and into our eyes, making them appear green. The fact that leaves don’t usually appear blue or red means that they absorb those parts of the light spectrum and use them to grow. The effect of blue light on plants is directly related to chlorophyll production. Plants that receive plenty of blue light will have strong, healthy stems and leaves. Red light is responsible for making plants flower and produce fruit. It’s also essential to a plant’s early life for seed germination, root growth, and bulb development.
Red Light or Blue Light for Plants?
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 (this is a particular problem for Christmas cacti that refuse to bloom at Christmas), 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. Sometimes, pollution can block essential light. If your unhealthy plant is next to a particularly dirty window, the solution to your problem could be as simple as giving it a good cleaning to let in as much light as possible.
