Gardening Under Lights

Our indoor garden resource page is packed with useful information about how you can be successful growing plants under artificial lights. The advent of the fluorescent light bulb has made indoor gardening more common and more efficient — a hobby that anyone can enjoy. Indoor gardening has many appealing uses:

• Getting a head start on the season. Gardeners in any part of the country can get seeds started and seedlings ready for the garden while it's still cold outside. This is quite useful for those who live in regions with short outdoor growing seasons.

• Growing a kitchen garden with fresh herbs all year long.

• Gardening all year long. It’s perfect for the gardener who refuses to give up the hobby during the wintertime.

• Propagating new plants from cuttings.


• Extending bloom times dramatically on many flowering plants.

• Enjoying gardening in general. Those whose lifestyle or location make outdoor gardening difficult or impossible can still enjoy the hobby.

Gardening outdoors leaves you at the mercy of the elements. Indoors, you are in charge. You can't blame the weather now. Are you ready to take the challenge?

How

Plants need two types of light waves for optimal growth and flowering — red waves for inducing blooms and blue waves for overall growth. These waves are supplied naturally by sunlight. (Remember science class with ROY G BIV and the prism?) The task at hand for the indoor gardener is to replicate sunshine indoors. You can actually do this pretty easily with "grow light" bulbs. These fluorescent bulbs are specifically designed to provide the correct light waves for plants.

If you use more than one light fixture, have a maximum of 6" of space between the fixtures. Therefore, a 30" wide table would be perfect for two 12" wide light fixtures. The table should be sturdy enough to stand the weight of damp soil, seed trays, flower pots, etc.

How Much

Indoor gardeners have made a science of growing prize-winning specimens under lights. The experts know the exact amount of light to apply for the precise length of time for the specific plants they are growing. Matching the correct amount of lumens (the amount of light emitted by a light source) and foot-candles (the amount of light actually striking a surface) to your plant is the key. The farther away from the light, the less foot-candles.

For now, we'll leave that to the experts. Here are some basic guidelines:

• Hang the fixtures 6" - 12" above the plants (12" being the maximum). You can hang the lights as close as 4", just make sure they do not touch the plants.

• Adjust the light fixture as dictated by plant growth (use the s-hook and chain mentioned above). Raise the lights as the plants grow. An alternate method is to raise and lower the plants themselves using a brick or block underneath the container.

• Make sure the lights are installed properly. The proximity to water makes safety a major consideration. Use a surge suppressor or power strip with the fixture.

• Make sure you buy a timer rated with sufficient wattage capability to match the lights.

• Keep a watchful eye on your plants. If leaves begin to turn brown, increase the distance between the light and the plant. If the plants start to look spindly, move them closer to the light.

In spite of all of this talk about light, remember that plants also need a period of dark to rest.

How Long

Flowering plants usually need 16-18 hours of light per 24-hour day. Foliage plants and seedlings getting ready for transplanting outdoors need 12-14 hours a day. A household timer is perfect for monitoring the amount of light. Make sure your timer is rated to handle the wattage of the light fixture(s).

For best results, the amount of light you provide needs to match the day length requirements of the plant. The term applies to each individual plant variety's specific light requirement. The proper amount of light (whether natural sunlight or artificial grow lights) is critical in order for the plant to grow and induce dormancy, but especially important for flowering and blooming. The three types are:

• Short day - requiring short days and long nights. Less than 12 hours of light a day.

• Long day - requiring long days and short nights. 12-16 hours of light a day.

• Day neutral - will bloom under either scenario.

Seed Starting

Your table and light setup can be used for seed starting. After germination, the light should be practically touching seedlings. Be sure to move as the seedlings grow.

If you plan on using your light table for starting seeds, remember that not all seeds need light to germinate. Some, like pansies, require dark. Do your homework.

Also Remember

• Plants that are grown under lights are experiencing the best growing conditions. You may need to increase watering and fertilizing to help them keep up. Keep an eye on the plants — some respond quite well to artificial light and may grow rapidly. Don't let them touch the light source.

• Air circulation is important to keep plants free of disease.

• Since artificial lights produce very little heat, you will need to make sure that the growing area is in the proper temperature range for the plant(s) you are growing. In general, Tropicals will need 70°-80° F daytime. Hardier plants will need a 65°-75° F range and about 5°-10° cooler at night. Invest in a good thermometer to monitor the temperature.