Sunlight contains the full spectrum of light that plants need to grow, but plants growing indoors need lighting supplements to provide the energy for photosynthesis. Blue and red light waves are the two primary colors that your indoor plants need to thrive; different plants require different levels of each. Select your indoor lighting based on the types of plants you are growing in combination with the amount of daily sunlight your plants receive.
High pressure sodium lights, HPS, are one lighting choice for indoor growing that emits a red orange glow. Red and orange light waves trigger hormones that increase budding, flowering and foliage growth. Plants cannot grow well with only red light waves; too much red light can cause a plant to become spindly. HPS lights are good companion lights for indoor growing conditions with some natural sunlight or other lighting sources that have high levels of blue light waves.
Metal halide lights are a good lighting choice for growing your plants indoors when there is no sunlight available. Metal halide lighting emits more light rays in the blue spectrum. Blue light regulates the rate of a plants growth as well as other plant responses including stomata opening. Stomata control the amount of moisture a plant receives and loses. Combine metal halide lighting with another source of red lighting such as HPS, fluorescent or incandescent for optimum results.
Fluorescent grow lights are the most common options for homeowners growing plants indoors. You can purchase different types of fluorescent bulbs that are higher in red output for growing flowers or full spectrum with a blue emphasis for promoting foliage. Fluorescent lighting works best for indoor plants when they are placed no more than two feet away from the plant.
LED lighting systems include separate lights for both red and blue lighting. A typical LED lighting system includes two red lights and one blue light on a track that hangs over your indoor growing area. LED lights are the newest option for indoor growers and claim to offer more lighting for less electrical output. The lights cast a red and blue glow over the plants, creating an unusual appearance.
Incandescent Spot Lights
Incandescent lighting should only be used to supplement other lighting sources for indoor growing. Incandescent spot lights are inexpensive, compared to metal halide, LED and HPS, but the plants do not absorb much of the light rays incandescent bulbs emit.