Everyone has seen them--sad, drooping indoor plants, looking forlorn and neglected. Though several skipped waterings can make a plant look weak and ratty, many indoor plants are deficient in an equally essential element---light. Many flowering plants fail to rebloom after purchase primarily for this reason. A lucky few homeowners will find themselves with a perfectly sunny room in which plants flourish, but most homes are simply too dim for houseplants to be happy. Artificial grow lights are one potential solution.
Elements of Light
White light, when broken by a reflective surface such as a prism or raindrop, scatters into the well-recognized rainbow. Plants primarily require only two colors of this spectrum, blue and red, while green, yellow and orange light are virtually useless to plants. Blue light encourages foliage growth, while flowering requires red light in combination with blue light. Sunlight provides the proper wavelengths of light, and several types of inexpensive fluorescent tube lights furnish light in the range necessary for healthy plant growth and flowering.
Benefits of Natural Light
Whether it is filtered through the boughs of trees or shining directly down, sunlight is the primary requirement for healthy plant growth and flowering. Though many types of common houseplants are tropical species, such as dracaena and philodendron, the vast majority of these occur as understory plants, or specimens that naturally require only low levels of sunlight. These types of plants do well in most homes and do not necessarily need an additional source of light.
Plants not receiving enough light usually look leggy, with long, thin stems and sparse foliage and leaves that appear yellowed or washed-out.
Drawbacks of Natural Light
Flowering plants, on the other hand, typically require more hours per day of bright or direct sunlight to produce blossoms. Orchids and African violets are familiar culprits, which often flower the first year they are purchased but never again. While a sunny, south-facing window may provide enough light for flowering plants to bloom, the interior of a typical home is too dim for most plants to produce flowers. Putting plants on windowsills can also stress them, as temperatures there fluctuate widely. In instances in which indoor gardeners want to encourage plants to flower, providing an additional source of light is usually necessary.
Examples of plants kept indoors that require generous amounts of light are cactus, citrus plants, kalanchoe, poinsettias and aloe vera.
Benefits of Grow Lights
Artificial lights, such as full-spectrum fluorescent lights and specialized plant "grow lights," make it possible to start all variety of seedlings indoors, encourage houseplants to bloom and promote healthy, vigorous growth. Grow lights are available in all sizes, from less than 1 foot long up to industrial-sized light fixtures of 48 inches or more. Look for lights between 500 and 5,000 lumens, the measurement of a light's brightness.
Common indoor plants that benefit from a bit of additional light include African violet, amaryllis, begonia, spider plants, weeping fig and Boston fern. By carefully researching a plant's light and humidity requirements in its native habitat, gardeners should be able to encourage most flowering houseplants to rebloom year after year. Even low-light tropicals will display lusher, greener growth, provided that it is well-watered and properly fertilized as well.
Drawbacks of Artificial Lights
Traditional incandescent bulbs are not good sources of light as they do not produce enough blue light. Incandescent lights are also much hotter than cooler fluorescent tubes and can easily scorch tender plants. Some version of full-spectrum fluorescent tube light will almost always be the proper choice for indoor grow lights.
Another factor to consider is whether the plant will need an additional source of heat. Grow lights for seedlings, for instance, should be used in conjunction with a seedling heat mat, which encourages germination and vigorous early growth.
Plant-light setups can appear cumbersome and clunky unless the stand and light can be cleverly disguised or masked. Most fluorescent tube harnesses look rather industrial and may not mesh well with the gardener's interior décor.