How Long To Keep Grow Lights for Indoor Plants? It’s best to know if the plants you chose to grow are considered as low, medium, or high-light plants. Low-light plants would only need about four hours of light exposure, while medium-light plants would need about six hours. When it comes to high-light plants, some needs 14-16 hours of exposure to artificial lights. If you have no clue as to what high, medium and low-light plants are, you can always check the box of the seeds you got. If there’s no indication of how much light the plants that you have a need, here is a guide that you may use:
High-Light Plants: Araucaria Plant Schefflera Arboricola Ponytail Palm Tree Yucca Plant Ficus Benjamina Ming Aralia Plant Ficus Pandurata Codiaeum Petra Chrysalidocarpus Lutescens Aloe Vera Coleus Burro Tail
Medium-Light Plants: African Violet Bird’s Nest Fern Boston Fern Dumb Cane Moth Orchid Moon Valley Pilea Chinese Money Plant
Low-Light Plants: Maidenhair Fern Staghorn Fern Philodendron
Snake Plant Asparagus Fern Weeping Fig Elephant’s Ear Fittonia Bear’s Paw Fern Earth Star Those are just a few plants that fall under the categories listed above. Take note of this to help you decide how long you should be turning your grow lights on and off.
How Many Hours a Day Are Needed for Indoor Plant Grow Lights? Light Spectrum The quality of light impacts how much light a plant needs. Plants primarily need light on the red and blue spectrums, which are best provided by using a full-spectrum fluorescent bulb or bulb labeled as a grow light. Another option is to use two fluorescent tubes, one warm white and one cool white, to provide a more complete spectrum. Incandescent bulbs only provide light on the red spectrum. They also have a shorter life and produce substantial heat, which can damage heat-sensitive plants. Lighting Intensity Light intensity is measured in foot candles. Most houseplants require between 50 and 1,000 foot candles from either artificial sources or from sunlight. If the plant only requires low light or receives some light from a window, regular lighting from ambient light fixtures in the room may be sufficient. Plants that require medium light require at least 250 foot candles, so they will grow better with a small grow light fixture if they aren't near a sunny window. Seedlings, especially vegetables and other that thrive in full sun, require 1,000 foot candles or more of light intensity, so intensive grow light fixtures that contain at least four light tubes are necessary for healthiest growth. Light intensity also varies depending on how close the plants sit to the light. For example, plants sitting 6 inches beneath a two-light fixture receive 500 foot candles, while those setting 3 feet from the light source only receive 60. Seedlings and High-Light Plants For best growth, place seedlings and high-light beneath a four-tube fixture containing full-spectrum lights. Set them about 6 inches beneath the lights so they can receive about 900 foot candles of light intensity. You can use a two-tube fixture, but the light intensity will be less and the plants may not grow as well. Seedlings require about 16 to 18 hours of artificial light daily. Ensure they receive even lighting and the maximum light intensity by placing reflectors around the light fixture, which will reflect all the light onto the tops and sides of the plants. Low- and Medium-Light Plants Most common houseplants can grow well with 12 to 14 hours of artificial light if they aren't receiving any sunlight. Medium-light plants require about six hours of daily sunlight, so
they benefit from a higher light intensity and do best when set no more than 1 foot away from the lights. Low-light plants typically grow well in shade or with less than four hours of direct sun, so you can set them 2 to 3 feet from the fixture. Although these plants have differing intensity needs, the amount of lighting time is the same when it's supplied by artificial means. If your plants receive some daytime sun but less than fits their needs, such as from a nearby window, provide them with an additional two to six hours of artificial light in the evening.