Distance Between Plants and Light
The proximity of the bulbs to your plants is very important because it affects light intensity. The closer the bulb, the greater the intensity. Plants that normally grow outdoors in full sun require the highest light intensity. This includes most flower and vegetable plants, orchids, gardenias and citrus. For these plants, the bulbs should be very close - no more than 3" away from the foliage*. This need for intense light holds true for seedlings too (your vegetable and flower seedlings will grow tall and spindly if they are too far away from the bulbs).
Most common flowering houseplants do not require as much light intensity. African violets and begonias will be quite happy 10-12" away from the light bulbs. Nonflowering tropical plants such as philodendrons and ivies can be placed as much as 36" from the bulb.
If you're growing different types of plants under one light fixture, you may need to vary the height of the pots. Place light-loving plants on an upside down flower pot to get them closer to the light. Your plants will also receive the best light intensity if they are placed under the middle section of the bulb, rather than the ends.
As your plants grow, raise the light fixture to maintain the appropriate distance between the top of the plant and the bulbs.
Leaving the Lights On
No matter what types of plants you are growing indoors, you must be sure to always give them time to "sleep". 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 growth rate and the setting of buds and fruit.
Like people, plants differ in the amount of rest they require. They are categorized according 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 per day. In fact, these plants usually require a series of even shorter days (less than 12 hours) before they will set buds and flower.
Long-day plants require at least 14 to 18 hours of light each day. Vegetables and most flowers fall into this category. Day-neutral plants, which include non-flowering foliage plants, as well as geraniums, coleus, and African violets are usually satisfied with 8-12 hours of light all year-round.
Using automatic timers is the best way to ensure that your plants receive the right duration of light each day. Group your plants under each light fixture according to what day length they prefer and your indoor gardening adventures will be easier and much more rewarding.
Water and Humidity
Seedlings and other plants that are placed close to warm light bulbs will require watering daily or every other day, to keep the soil from drying out. If you're using our Accelerated Propagation System (APS), check the water level in the reservoir twice a week.
Your houseplants may require less water if they are placed further away from the light fixtures (room temperatures can also affect how frequently you have to water). Water houseplants once or twice a week, allowing the soil to dry out between waterings.
Many plants, including most orchids require high humidity as well as adequate water. You'll need to pay more attention to this when they're growing under lights. To create a humid environment, fill a shallow tray with gravel or marbles, set the orchid pot on top and then cover the gravel with water. The water will evaporate around the pots to create a more humid environment. You may need to experiment for the first two weeks to determine a good watering schedule.
Getting the Most Light From Your Bulbs
If you've designed your own lighting unit, paint your growing trays white, or use foil-covered reflectors to increase the amount of light your plants receive.
When the ends of a fluorescent tube darken, it means that the light is aging. Light output from an old bulb can be less than half that of a new bulb. Replace the bulb when necessary.
Be sure to clean your fluorescent tubes monthly. An accumulation of dust and dirt can dramatically reduce the amount of light your plants receive.
Guaranteed Easy-to-Grow Plants
You can grow almost any plant under lights if temperature and humidity are right! Garden newcomers will have good success with easy-to-grow seeds like zinnias, marigolds, tomatoes, and cucumbers. Easy-care adult plants include: begonias, ferns, geraniums, oxalis, jade, philodendrons, and all types of succulents. If you like the cactus members of the succulent family, they're the easiest of all!
High intensity 4-bulb fixtures put out twice the light. They are ideal for winter tomato plants, flowering exotics, or specialty orchids.
Gardening Success Guaranteed
Garden Lab Designed & Tested
Support a Community that Cares
Expert Garden Advice