The Best Lights for Plant Growth

Indoor gardeners use artificial lights and choose plants that do not need full sun for indoor gardens. Some build large light assemblies that run up to 14 hours a day. Successful gardeners use a variety of the best sources to provide balanced light for their houseplants because they know that too little of the right kind of light will lead to pale, stretched, leggy growth on plants that seldom bloom.

Sunlight

All plants have evolved, whether under cover of rain forest canopies, in wide open deserts or on frozen tundras, under the same sun. The sun naturally emits the exact balance of colors to create the “white” light upon which plants depend to produce chlorophyll, the essential element for food production. Indoor plants kept near windows where they receive nearly the same amount and daily length of sunshine as they would outdoors generally do better than plants kept under all but specially designed artificial light cabinets. Some plants, particularly those that grow under cover of trees or larger plants, make better house plants than others because they thrive at lower levels of sunlight. Most of these plants are tropical rain forest and jungle natives.

Fluorescent Lights

Early fluorescent lights produced blue-heavy light. Blue light is great for vegetative growth but both red and blue light are needed for flowering. Indoor gardeners solved the problem by adding incandescent lights, which produced red-intensive light. Fluorescent lights could be placed close to plants to maximize light availability but incandescent lights produced heat (infrared) as well as light and had to be positioned farther away. New high-output fluorescent lights produce a greater amount of red light, providing a more natural “daylight” in a more efficient manner and without the heat of incandescent lights. Special “grow” lights are available in both fluorescent and incandescent forms but fluorescent lamps provide the most efficient, coolest and easiest to use light source for many indoor gardens, according to Purdue University’s Extension Service. The University of Missouri Extension recommends using fixtures with reflectors to get the most light out of any artificial source.

New Lighting Options

Progressive Gardening cites high output and compact fluorescent lamps for balanced light and suggests newer types of high-intensity discharge (HID) lights that provide high-quality light for indoor plants that been proven in commercial greenhouses. Metal halide (MH) lamps provide a white light that is closer to that of the sun than any lamp available and lasts up to 25 times as long as comparable incandescent grow lights. The second HID is a new version of the efficient sodium vapor streetlight adjusted to produce more orange-red spectrum light, the high-pressure sodium lamp (HPS). MH and HPS components can be put in common reflectors to create lighting instruments that combine percentages of light from MH and HPS lamps or switch from a blue-heavy MH lamp to a red-intensive HPS lamp for flowering and fruiting.

Keywords: indoor plant lights, houseplant grow lights, indoor gardening hints, high intensity discharge, flourescent plant lights

About this Author

Chicago native Laura Reynolds has been writing for 40 years. She attended American University (D.C.), Northern Illinois University and University of Illinois Chicago and has a B.S. in communications (theater). Originally a secondary school communications and history teacher, she's written one book and edited several others. She has 30 years of experience as a local official, including service as a municipal judge.