Gardening Under Lights
Efficient grow light stands bring the sunshine indoors
Grow lights are perfect for indoor seedstarting. You can also use them to grow light-loving houseplants, such as orchids.
Grow lights, such as this Compact 2-Tier SunLite Garden, are attractive enough to have in the kitchen. Our Vermont-made line of SunLite Gardens includes both standard (4 feet wide) and compact (2 feet wide) models.
The benefits of growing under lights are hard to ignore. There is simply no better way to grow an abundance of stocky, green seedlings. If you grow flowering plants indoors, such as orchids, African violets, citrus and hibiscus, lights will keep them blooming almost year-round. A wintertime harvest of herbs and salad greens can also be grown with lights.
By learning how plants use light and about the fixture options, you can select an indoor lighting system that is right for the plants you want to grow.
The Right Color
Sunlight contains the complete spectrum of light including all colors of the rainbow: red through yellow to blue and violet. Plants use the full spectrum for photosynthesis, although red and blue light seem to be most critical. Red light stimulates vegetative growth and flowering, but if a plant gets too much red light, it will become tall and spindly. Blue light regulates plant growth, which makes it ideal for growing foliage plants and short, stocky seedlings.
The Right Intensity
The intensity of light that a plant receives is determined by the wattage of the bulb and by how close the plant is to the light source. Just as plants differ in their need for certain colors of light, they also differ in their need for light intensity. Typically, those plants that are native to tropical jungles or shady forests do not require as much light as plants that evolved in dry, sunny climates, such as the Mediterranean or southern Mexico.
Most flowering houseplants, such as African violets and begonias, are happy being 10 to 12 inches away from a light source. Foliage plants, such as ivy or philodendron, can be placed as much as 36 inches away from a light source. But many flowering plants, such as orchids, gardenias and citrus, as well as most vegetable plants, require a much higher light intensity to flower and produce fruit.
Growing Tips for Fluorescent Bulbs
- Rotate your plants each week. The light from a fluorescent bulb is more intense at the center of the bulb than it is at the ends.
- Replace fluorescent tubes when the ends darken. That means the tube is old and the light output may be less than half of a new bulb.
- Clean your fluorescent bulbs each month. Dust and dirt can dramatically decrease the amount of light emitted.
- Place your hand where the light hits the foliage. If you feel any warmth, the light is too close.
The Right Duration
No matter what types of plants you are growing indoors, you must be sure to give them a rest. When it's dark, plants respirate, which is an important part of their growth process. The balance of rest time to active growth time affects many biological processes, including the growth rate, and the setting of buds and fruit.
Botanists usually divide plants into three categories relating to their preferred day length: short-day, long-day or day-neutral.
Short-day plants, such as chrysanthemums, kalanchoe, azaleas and begonias, will thrive on less than 12 hours of light per day. In fact, these plants must usually go through a series of even shorter days before they will set buds and flower.
Long-day plants require at least 14 to 18 hours of light each day. Most vegetables and garden flowers are long-day plants, and when they don't receive enough light they get pale and leggy.
Day-neutral plants, including foliage plants, geraniums, coleus and African violets, are usually satisfied with 8 to 12 hours of light all year-round.
Using Fluorescent Bulbs
Fluorescents produce two to three times more light than incandescent bulbs for the same amount of energy. They are the most inexpensive lights for indoor gardening. The color of light produced is determined by the phosphor coating on the inside of the bulb.
Full-spectrum fluorescent bulbs, such as our SunLite bulbs, produce a balance of cool and warm light that replicates the natural solar spectrum. These lights are excellent for seedlings as well as houseplants, culinary herbs and other plants. The bulbs in our SunLite Gardens are some of the best full-spectrum bulbs on the market, replicating 98% of the solar spectrum. The bulbs use less electricity and last significantly longer than standard fluorescent bulbs. To learn more, read Why Our SunLite Grow Lights Are Better.
Cool white bulbs are a good source of blue and yellow-green light, but are a poor source of red light. They are used for interior lighting in schools and office buildings, and are the most commonly available type of fluorescent bulb. Plants grown under cool white bulbs will be stocky or even slightly stunted.
Warm white bulbs emit plenty of orange and red light, but less light in the blue and green spectrum. If you are growing seedlings under 2-bulb fluorescent fixtures, you can usually achieve a good color balance by combining one cool white and one warm white bulb.