Growing Plants Indoors With Grow Lights
Grow lights for indoor plants make it possible to sustain your family with healthy, organic, homegrown foods — whatever the weather — as synthetic rays reproduce the sunlight necessary for photosynthesis. Photosynthesis is how plants use carbon dioxide and water to produce food and release oxygen.
Whether you use plant grow lights to start seeds indoors before transplanting mature plants outdoors or you want to create a dramatic indoor herb garden with floating shelves for year-round use, our guide helps you explore and understand your options.
Types of Grow Lights
Like all light bulbs, grow lights are available in indoor and indoor-outdoor versions of four basic categories.
Check the bulb manufacturer’s placement recommendation before installing to ensure it’s safe for use in an outdoor greenhouse or, alternatively, your home.
LED Grow Lights
LED grow lights are the newest and most economical entry in this market. With the highest possible energy efficiency, your indoor garden’s energy usage is nearly imperceptible and offers the longest bulb life. Additionally, the best LED grow lights produce very little to no heat, eliminating the possibility of scorching tender plants and making this the perfect bulb for both beginners and advanced growers. Natural light options are available in LED grow lights as well.
Fluorescent Grow Lights
Growing with florescent lights offers several distinct benefits. Fluorescent grow lights have a lower light output and different Kelvin rating (a measure of heat output) than LED lights, which may produce a blue or purple tint in your growing area. With a lower light output, which is ideal for starting plants, fluorescent grow lights use less energy than incandescent bulbs but aren’t as economical as LEDs.
Integrated LED Grow Lights
Integrated LED grow lights combine light spectrums for ultimate convenience. Using a combination of blue for leafy greens and red for flowering, home growers get the benefit of both light types without rotating lights regularly, which is recommended for successful in-home farming. However, you don’t have to worry — red and blue grow lights don't make purple lighting. The light spectrum is imperceptible to the human eye. LED lights cast a pleasing white light that blends seamlessly with your home’s lighting scheme.
Grow Light Styles
Grow light bulbs are available in a variety of styles to suit your home’s indoor gardening space.
- Traditional E26 bulbs are ideal for small spaces and single plants.
- Linear bulbs are available in 2- to 4-foot lengths and are great for tiered corner gardens.
- Panel lights suspend above plants and come in a variety of sizes for small and large indoor growing zones.
If you’re growing in a small space, your bulb’s temperature matters. Gone are the days of purple-only options. Check the Kelvin rating of the grow light you want to buy, as many bulbs are now available with a pleasing white light that blends seamlessly with your home’s other lighting.
Grow Light Spectrum
The light spectrum referred to when discussing indoor grow lights isn’t visible to the naked eye. The light spectrum refers to the wavelengths of light produced by the source to promote growth. Different colors, therefore, promote different growth.
- Violet/blue light ranges between 400 and 500 photosynthetically active radiation (PAR) and is ideal for new growth.
- Green light ranges between 500 and 600 PAR, ideal for thick growth.
- Red light ranges between 600 and 700 PAR and fosters late-stage growth and flowering.
- Far red light is 700 PAR and above and is often used to speed flowering.
Promote growth by rotating your lights based on the age and stage of your plants. Or use an integrated bulb that combines several lights.
- For general growth, a balanced red-to-blue light ratio of 3-to-1 is great for leafy greens and herbs, as both produce chlorophyll A and B.
- Reproductive plants will thrive in a 6-to-1 red-to-blue light ratio designed specifically for the needs of flowering or fruit-bearing plants.
Deciphering Grow Light Language
- PAR: photosynthetically active radiation. PAR is measured in wavelengths of nanometers, typically 400 – 700.
- PPF: photosynthetic photon flux. PPF is measured in micromoles per second and translates to the amount of light the lamp emits.
- PPFD: photosynthetic photo flux density. PPFD refers to the amount of light that actually reaches the plant when factoring in light angle, reflectors, the fixture itself and the distance between the light and the plant. PPFD is impacted by the age and stage of the plant, which is why it’s important to change your grow lights depending on plant maturity.
- DLI: daily light integration. DLI indicates how many active protons reach a given area in a 24-hour period. For low-light plants, like leafy greens and herbs, a DLI of 12 or more will produce sufficient growth. For high or advanced red-light plants, like garden vegetables, a DLI of 20 – 30 should do the trick.
Quick Tips for Working With Grow Lights
- Like everything, plants need rest. Arrange for at least 8 hours with the lights out each day. If you have trouble maintaining a schedule, put your grow lights on an automatic timer.
- Place grow lights about 12 inches from your plants for the best performance.
- Don’t pack your plants tightly underneath the grow lights. Allow space between each plant to ensure air movement. Add a small fan to circulate air around each plant. Space and air movement prevent fungus from growing in your containers.
- Research and experiment to find the ideal conditions for growing inside of your home. Plants and homes are unique in the amount of natural light and airflow that exists. Play with different lights, platforms and fans to discover the optimal conditions to create happy, healthy plants.