How Long Do Grow Lights Stay On?

Pansies are day-neutral plants.

Grow lights make it possible to start seeds or grow plants in places where the sun never shines, such as indoor environments. Many types of grow lights are available, from simple shop lights to expensive, sophisticated metal halide.

Short-Day Plants

Short-day plants include the asters, salvias, poinsettias and kalanchoes. These plants require about 12 hours of artificial light each day. Keep the grow lights 3 to 5 inches above the top of the plants, and raise the lights as the plants grow taller.

Long-Day Plants

Long-day plants include hibiscus, larkspur and delphinium. They need about 16 hours of artificial light daily. Allow long-day plants rest with no light for about eight hours each day.

Day-Neutral Plants

Day-neutral plants include geraniums, pansies and snapdragons. They are not fussy about the number of hours of artificial light they get and will respond well to the amount of light given to a short-day or long-day plant.

Starting Seeds

Keep seeded flats and flowerpots under artificial light for 12 to 14 hours each day to give them the photosynthesis they need to grow into strong, healthy plants.

References

• North Dakota State University: Artificial Lights for Indoor Plants
• Science Dictionary: Day Neutral