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Do grow lights work? How to make sure you’re not wasting your money

Your guide to picking out the just-right grow lights

A small plant under a grow light
nikkytok / Shutterstock

It’s never been easier to garden indoors. Today, you can use grow lights to help cultivate many kinds of plants all year long, no matter where you happen to live. But do grow lights work? Yes! Grow lights are designed to be a sunlight substitute that stimulates the photosynthesis process within plants by providing them with the right color spectrum.

You can grow all your favorite herbs, fruits, and vegetables year-round by using the correct bulb or fixture. Several kinds of grow lights are available on the market, with each having its own strengths and weaknesses. If you’ve been wondering whether grow lights would be an excellent investment for your greenhouse, we’ve got the answers.

Vegetables under artificial light
zhang sheng / Shutterstock

What are grow lights, anyway?

Greenhouse grow lights are essentially artificial lights. Some are designed to shine with a light spectrum like that of the sun. Others provide a light spectrum that’s customized to the specific plants in your greenhouse. With grow lights, you’re able to copy specific spectral outputs, colors, and temperatures of light. Plus, you can vary the overall intensity of the light these bulbs and fixtures put out.

Do grow lights actually work?

In short, yes. However, many feel that they work only when you choose the right kind of light. While all grow lights promise to mimic the sun and provide the color spectrum and temperature necessary for proper photosynthesis, there are some who don’t completely buy into the marketing hype surrounding them.

What do grow light colors mean?

Plants will flourish when you expose them to all the colors on the light spectrum, but they don’t necessarily require the same amount of each color. Within the visible light spectrum, red and blue are two of the most important light colors for plants, although plants use other colors, too. These colors are on opposite sides of the spectrum, with red featuring the longest wavelength whereas blue has the shortest one.

When combined, both are crucial for photosynthesis, assisting with the absorption of chlorophyll. Red is specifically important for flower growth while blue supports root development. You’ll often see grow lights emit a purplish light, as manufacturers will combine both lights to bolster plant growth.

Vegetables under grow lights
asharkyu / Shutterstock

What types of grow lights are on the market?

There are three different types of “traditional” lights that people use to grow plants.

  • High-pressure sodium lights
  • Fluorescent lights
  • Metal halide lights

Today, advances in technology have brought LED lights into the grow light competitive arena. However, it’s the LED lights specifically that some greenhouse owners feel aren’t living up to the publicity surrounding them.

High-pressure sodium lights

For those growing fruit and flowers, these types of lights are the most popular by far. High-pressure sodium lights produce intense, bright light that contains most of the oranges and reds within the color spectrum.

A downside is that they also get incredibly hot. If you use these kinds of grow lights, you’ll need to ensure that your greenhouse is well ventilated and that you manage the overall temperature inside.

Fluorescent lights

If you’re working with plants that need lower light levels or are starting new seedlings, then fluorescent lights are a perfect choice. Typically inexpensive, these types of lights are available at many stores. Also, they’re easier to use than any of the other grow lights on this list.

Be that as it may, these grow lights aren’t that great as primary light sources. Used as secondary lighting, however, fluorescent lights can be pretty effective.

Metal halide lights

Of all the lights we mention here, metal halide lights provide light that is closest to that of the sun. They work with all types of plants and are rated with a lumen output of about 100 lm per watt, lasting for up to 20,000 hours. That means you could run them almost continuously for around three years straight before having to replace them!

However, a particular downside is that these lights also become incredibly hot. Touching one after it’s been turned on for a while can result in significant burns.

Greenhouse LED grow lights

There are some substantial benefits to using LED grow lights, even though some people, as mentioned above, don’t feel the technology is quite up to the standards of traditional lighting. However, LED lights have the following going for them:

  • They’re environmentally friendly in that the lights are mercury-free and don’t shatter like glass.
  • They last five times longer than fluorescent bulbs and use half the electricity.
  • They produce a full spectrum of light, just like fluorescent lights on this list.

The problem here is that any energy and cost savings you might realize by using LED lights are negated by their initial cost, which can be rather expensive. Another downside is that LED light is more direct and less diffuse than more traditional lighting systems.

Greenhouse in private area
Aleks Kend / Shutterstock

Are grow lights a good investment?

It’s an undeniable fact that plants grown in greenhouses yield a greater harvest when they’re provided healthy amounts of photosynthetic light. You’ll wind up with more leafy greens and larger, juicier fruit when your plants receive the light they need.

With that said, when winter arrives, the amount of sunlight decreases. Many geographic locations see significant dips in photosynthetic light in the colder months. For those who want to grow and harvest year-round, a grow light system that can supplement natural sunlight is an investment that makes sense.

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Will Blesch
Former Digital Trends Contributor
Will Blesch is a copywriter, content writer, and someone passionate about anything that lets him discover more about this…
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