Do Different Types of Artificial Light Affect Plant Growth?

Foliage

• Light from the blue and violet portion of the spectrum stimulate green growth on plants, such as that of foliage. Metal halide grow lights are a good source of blue and violet spectrum lighting. These produce a light similar to the light outdoor plants experience in early spring, when they are just beginning to develop and grow. This type of lighting is best for leafy green plants or as a primary light source for any plant that receives no supplemental natural sunlight. Fluorescent lights ranging from 5,000 K to 6,500 K are another source of blue spectrum light; K stands for kelvin, a unit of measurement for temperatures in lighting.

Flowers and Fruit

• Lamps producing light in the orange and red portion of the spectrum are best for flowering and fruiting plants. This type of light is similar to that of summer and fall, triggering hormones within plants that increase their flower and fruit production. The most efficient source of orange and red spectrum lighting is a high-pressure sodium light. These lights are economical, using little energy, but should be used as a supplemental light rather than as a sole source of light for plants. Fluorescent lights in the 2,700 K to 3,000 K range are also ideal for flowering and fruiting plants.

Plant Size

• The size of plants matters if they are being grown in an area with space restrictions or when they remain healthier or more productive at a certain size. Metal halide lights create compact plant growth, while high-pressure sodium lights increase height and vertical growth. Fluorescent lights produce a full-spectrum light that does not affect the size of plants in terms of growing tall or growing lower to the ground. Rather, these types of lights are best used for shorter, low to the ground plants like seedlings, as they are placed very near the tops of the young plants and make the light accessible and warm to stimulate new growth.

Health

• Metal halide lights are efficient at producing plants with good overall health. These lights encourage the plants to develop strong, sturdy root systems and dense, compact growth. Both of these plant qualities work together to increase the plant's disease resistance and make for stronger plants. Metal halide lights are ideal for young plants to promote health early on, making for a lifetime of vitality.