How Colored Lights Affect Plant Growth

Overview

Colored lights affect plant growth through photosynthesis, but different plants require different levels of colored light to thrive. Colored light energy can promote flowering, affect growth direction and impact the plant's ability to retain water. Sunlight has every color that your plants need to grow, but indoor plants need colored light supplements to provide the necessary light energy for optimum growth.

Photosynthesis

Plants use photosynthesis to turn light energy into the food and oxygen needed for growth. Sunlight contains the full color spectrum of light energy needed for photosynthesis. Light energy refers to the wavelength, or color, of light emitted from a light source. Other sources of light emit heavier concentrations of specific colors, such as red or blue, to trigger growth hormones that are particularly useful to a specific plant type.

Light Quality

Each plant contains the phytochrome protein that allows it to sense "light quality"--- another term for the color of light. Plants use every color of the light spectrum, but red and blue lights have the greatest impact on growth. Blue lights work best with plants that do not flower; red light encourages flowering.

Light Quantity

The quantity or intensity of light quality also affects plant growth. Adjust the quantity of light with reflective materials or decrease it by providing shade and you will affect growth.

Response

A plant's growth pattern is directly influenced by light. A plant's roots grow away from the light and the stems grow toward the light. The color blue in a light spectrum controls the response to light, affecting this direction of the plant's growth.

Moisture

Blue light also affects plant growth by controlling the amount of water a plant loses or retains. Blue-colored light regulates the opening of the plant's stomata. The stomata are openings on the surface or just beneath the surface of the plant's leaves. If the stomata are open, the plant loses moisture; if the stomata are closed, the plant retains moisture.

Hormones

Colored light energy in shades of red and orange trigger plant hormones that increase budding and flowering. Even though red light stimulates foliage growth and flowering, too much red light energy causes a plant to become spindly. Blue light energy encourages seed growth, but red light energy affects germination. Far-red light energy impedes germination. Plants need a combination of both blue and red light energy for optimum growth.