MSU Researchers: LED Lighting Speeds Growth for Local Flower Growers

Researchers at Michigan State University in East Lansing are working on research that will help local cut-flower farmers grow their crops in a more sustainable and profitable way.
Roberto Lopez and Caleb Spall in greenhouse
Researchers at MSU are studying the effects of different colored LED lights on cut-flower farming. Pictured are Roberto Lopez, left, head of the project, and Caleb Spall, a graduate research assistant. // Photo courtesy of Michigan State University

Researchers at Michigan State University in East Lansing are working on research that will help local cut-flower farmers grow their crops in a more sustainable and profitable way.

About 80 percent of the cut roses, carnations, and chrysanthemums Americans buy are from other countries; the U.S. is historically one of the world’s leading importers of traditional cut flowers. Consumers are starting to buy more flowers from local growers, however, allowing for more diverse arrangements, supporting community businesses, and reducing the carbon footprint.

Michigan is the nation’s third leading producer of flowering crops.

“There’s a huge demand for specialty cut flowers,” says Roberto Lopez, an associate professor of horticulture in the College of Agriculture and Natural Resources. “There are more and more greenhouse cut flower growers coming along in Michigan and across the U.S.”

Specialty cut flowers are flowers other than roses, carnations, and chrysanthemums, where the supply isn’t dominated by imports. Lopez and his team are working to show how LED lights can cut growers’ energy bills and reduce production time.

Lopez’s flower greenhouse offers a humid environment with a temperature of 72 degrees Fahrenheit. Fans keep the air moving, and LED lights in various colors hang on mounted panels from the ceiling.

“Some plants need more than 12 hours of light to flower,” says Lopez, who is a researcher and instructor in the department of horticulture. “If you want to grow high quality plants in Michigan, you have to supplement sunlight with high intensity electric lights.”

Lopez also works with MSU Extension, sharing his expertise with Michigan’s commercial greenhouse operators. Lopez and commercial growers work year-round.

Currently, the industry relies on high pressure sodium lamps, or HPS lamps, for supplemental lighting. LEDs use less energy and come in a variety of colors; different colors can promote different growth properties in the plants.

The choices in colors and how long the lights are on are the variables Lopez is using in his experiments. He and his team are trying to find the best settings to grow the best cut flowers as quickly as possible.

“There’s not very much research out there,” Lopez says. “And there are so many questions.”

There is a significant investment in upgrading to LED lights, Lopez says. While the long-term savings are obvious, they can also help growers in the short run by accelerating plant growth, reducing time to harvest, and accentuating features that are most attractive to florists and consumers.

Growers have to understand which “treatments,” or light colors, are best for them and their flowers.

“We want to provide the growers the information they need to take those next steps,” says Caleb Spall, a graduate research assistant working on specialty cut flowers and a recipient of the 2021 Dave Dowling Scholarship from the Association of Specialty Cut Flower Growers. Spall is working with Lopez.

The team found that all red supplemental lighting treatment can elongate flowers’ stems, which can be an attractive feature to florists. Plants grown under all blue supplemental lighting flowered faster. It will take another growing cycle to validate the team’s findings, according to the researchers.

To ensure the observations are a consequence of the supplemental lighting, researchers must keep other variables, such as the greenhouse temperature and humidity, constant.

“It’s a big challenge,” says Nate DuRussel, a research technician overseeing the greenhouse’s floriculture projects. “Every day brings a different temperature outside, but we have a pretty high-tech control system inside the greenhouses. It never gets boring.”

DuRussel works with three different labs on more than 20 experiments.

Local growers can provide more reliable access to products than farms in Europe or South America can. Buying locally sourced products cuts down on the fuel needed to ship flowers, as well as the associated carbon emissions.

Flowers also start to wilt when they’re cut, so they’re stored and shipped cold to preserve their quality. Reducing the time it takes to get the flowers to consumers means better looking flowers and saved energy that would have gone into refrigeration.