How to Use Grow Lights for Indoor Plants (2024)

Whether your home lacks bright windows or other plants already occupy those windows, grow lights can be a helpful way to supplement light to your indoor plants that aren't receiving enough sun. But do grow lights actually work?

These artificial lights can increase a plant's ability to complete photosynthesis—however, grow lights are not as powerful as natural sunlight. They are still effective enough to be a simple solution that supports strong, healthy growth for most indoor plants.

Once reserved for commercial growers and hobby farms, grow lights are now widely available for residential use in various styles, sizes, and strengths. A grow light is a great option if you're struggling with a lack of natural light in your home.

Below, learn how to use grow lights to keep your favorite greenery healthy in low-light spaces at home.

Key Tips

• Grow lights produce light particles that plants recognize for photosynthesis or the necessary energy for plant growth.
• These specialized lights speed up growth and accelerate flowering.
• Consider the four growth light types: incandescent, fluorescent, LED, and high-intensity discharge.
• Grow lights are great for starting seeds, growing herbs, or providing supplemental lighting for plants not receiving enough sunlight from a window or indoor lighting source.
• Place grow lights within a foot of the plant.
• Give plants at least 12 to 14 hours of supplemental artificial lighting; do not run them around the clock. Plants need a daily rest cycle.
• A high-quality, full-spectrum grow light, when used correctly, can substitute for sunlight.
• If a plant is getting no supplemental sunlight, the plant might need about 16 to 18 hours under the grow lights, depending on the plant's light requirements (low-light vs. high-light plants).
  

Benefits of Grow Lights

Indoor plants require more light than most homeowners realize, and lacking natural light is an all-too-common houseplant ailment.

Grow lights increase the amount of usable light available to indoor plants. These lights can help improve nutrition, speed growth, accelerate flowering, and keep your houseplants alive and healthy indoors.

How Do Grow Lights Work?

Grow lights provide indoor plants with the light they need to photosynthesize. They can mimic the sun's full spectrum (called full-spectrum lights) or emit specific wavelengths in the blue or red ranges. Traditional light bulbs keep our homes nice and bright for us, but they don't do too much for plants, which require particular types of light to grow.

The best photosynthesis wavelengths on the visible light spectrum occur in the blue range (425 to 450 nanometers) and the red range (600 to 700 nanometers). Traditional light bulbs fall in the middle (500 to 700 nanometers). Red light supports flowering, while blue light supports vegetative and structural growth. However, both types of light are essential to supporting balanced, healthy plant growth.

Types of Grow Lights

Incandescent

Incandescent grow lights are the cheapest but also the least energy-efficient option available. They have a relatively low light output; however, their high heat output means they can’t be placed too close to any plants. Incandescent bulbs produce more red light than blue light.

Fluorescent

Fluorescent grow lights are more energy-efficient than incandescent lights. However, they tend to be more expensive. They produce a decent light spectrum for plants and lower heat output than incandescent bulbs. However, they can be fragile and don’t last as long as some other lights available, such as LEDs. Fluorescent lights are usually sold as tube lights, which are generally not as convenient for simultaneously lighting just a few indoor plants.

LED (Light Emitting Diode)

LED grow lights are energy-efficient, cost-effective, and provide an ideal light spectrum for all types of plants. Plus, they have a low heat output, so you won’t need to worry about burning your plants if you place the light too close.

High Intensity Discharge (HID)

Most commonly used for large-scale commercial growing operations, high-intensity discharge (HID) lights have an extremely high light output. They are also expensive and typically sold as large-scale installations versus small individual bulbs.

What Type of Grow Light is Best?

Most residential, small-scale applications and full-spectrum LED grow lights are the best choices. They are cost-effective, widely available, and energy-efficient, offering an ideal indoor plant light spectrum range.

Where to Put Grow Lights

The closer a grow light is to a plant, the more light the plant will receive. Ideally, a grow light or bulb should be placed about 1 foot away to ensure it gets enough light.

It is usually also best to place the light directly above a plant rather than off to the side, as this could cause the plant to grow sideways and “reach” toward the light. However, for some species, like trailing plants, having the light directly above the plant isn’t as important since they don’t grow upwards.

How Long to Leave Grow Lights On

Grow lights should be left on for at least 8 to 10 hours a day, which mimics the amount of natural sunlight plants are typically exposed to within a day. Putting your grow lights on timers can help automate this process so you don’t accidentally forget to turn your lights on or off. You can find light timers at most big box stores or online.

Indoor plants that are not receiving any sunlight might need up to 16 to 18 hours of light from a grow light for adequate growth, according to the University of Missouri Extension.