FARIBAULT, Minn. — The lettuces and herbs at Living Greens Farm, bursting from holes in towering plastic racks, are nourished by twinkling, Christmas-colored grow lights and sprays of nutrient-rich mist. The leafy greens never touch a speck of dirt and will be chopped and bagged into grocery store salad kits moments after harvest.

This aeroponic produce-growing operation churns out produce from a small office park warehouse on the outskirts of town. It may feel like a sterile science lab, but the company's chief executive is quick to argue that growing vegetables inside doesn't make you anything less than a farmer.

"We see ourselves as farmers first, understanding the plant and what it requires, using technology to enable growers to get the most out of their genetic potential," said George Pastrana.

Living Greens is among a cadre of Midwest vegetable growers pushing fast and hard to establish and scale indoor agriculture, a burgeoning industry driven by environmental, health and economic concerns.

Like any emerging or disruptive technology, many will try and some will fail as methods are perfected. But significant investor interest suggests possibilities beyond a niche market.

More than 90 percent of the U.S. supply of lettuce and leafy greens is grown in California and Arizona. Produce cultivated indoors is a small but growing segment of the overall market, as consumer demand for fresh and healthy food continues to grow.

Proponents pitch an array of benefits: less need for land, water and fertilizer, reduced national dependence on growers in the southwest as water shortages loom, and the lower transportation costs and fuel use that stem from growing food closer to the consumers who buy it.

"There's more of these farms popping up every year," said Natalie Hoidal, an expert on vegetable farming with the University of Minnesota Extension. "Not just these big facilities but also at the nonprofit and community level — small operations interested in neighborhood-scaled food production, in getting kids involved in growing food."

A February 2021 study by Markets and Markets Research valued the indoor farming technology market at $14.5 billion in 2020 and predicted that would grow to $24.8 billion by 2026.

"Indoor farming ... is looked upon as a potential solution for the growing concern about food security in the coming years," the report's introduction reads. Certain types of produce — tomatoes, leafy greens, herbs — have been particularly amenable to growing inside.

The Owatonna-Faribault corridor along Interstate 35 in southern Minnesota has become something of a regional hot spot for indoor vegetable productions.

Just a few miles from Living Greens Farm is the Owatonna headquarters of Revol Greens, which advertises itself as the largest greenhouse lettuce operation in the U.S. The company raised $204 million in venture capital in the second half of 2020. It recently opened a greenhouse in southern California, near the heart of the field-grown greens industry, and two more are scheduled to open soon in Georgia and Texas.

"We definitely think it's the future," said Brendon Krieg, co-founder of Revol Greens and vice president for marketing. Demand for the company's hydroponically grown lettuce and salad kits has more than doubled in the last 12 months, he said.

Several of the co-founders of Revol Greens had previous ties to Bushel Boy, an Owatonna company that's been growing tomatoes indoors for 30 years. The company recently began selling greenhouse-grown strawberries.

Salad kits from Living Greens can be found in grocery stores in Minnesota, Wisconsin and Illinois. But the company is undertaking its own ambitious expansion, with plans to open four new indoor growing centers in the Midwest, Northeast, Southeast and Southern United States by the end of 2023.

Pastrana, who took the top job at Living Greens last year and is guiding the private company toward a nationwide expansion, said there's another Midwest greenhouse in the works outside of Minnesota. The company will maintain its Faribault operation as a research and growing site, and is soon to open a new Twin Cities headquarters, he said.

Investors are increasingly interested in indoor-farming technologies, fueling private investment and company growth, Pastrana said. The company employs about 60 people in Faribault but hopes to have about 600 people on the payroll nationally by the end of the expansion, he said.

There are a variety of "ponics" systems used to grow indoor vegetables. Hydroponics involves growing produce in mineral-water solutions, while aeroponics loosely suspends the plants from growing racks, spraying them with a similarly nutrient-rich water.

Some startups in Minnesota and elsewhere have tried to harness another process, aquaponics — in which fish are raised in indoor tanks, fertilizing water that is then circulated to feed indoor-grown plants. These plants, often lettuce, then clean the water before it's recirculated back to the fish.

Greg Schweser, an extension educator at the University of Minnesota, said these processes show varying levels of promise for increasing sustainability in food production. But he cautioned that it can be tough to get right, especially on a larger scale, and he noted that many indoor growing operations and urban farm ventures failed to get off the ground in recent years.

"Overall it's been kind of a rocky start for indoor agriculture. Maybe some of these firms that are expanding nationwide have started to figure it out," Schweser said. "Greens are something of a low-hanging fruit, so to speak, but we do hope to develop systems that, over time, can host a broader range of crops and increase year-round revenue opportunities for Minnesota farmers."

The largest of three grow rooms at Living Greens has 32 racks — or what the workers call "systems." Each is 56 feet long and fits approximately 2,000 plants at a time. The harvested greens are cut and packaged in another part of the warehouse and shipped to stores. Customers often get greens that were harvested just a day or two earlier.

Revol Greens promises a similar turnaround. Both companies sell products at prices comparable to similar offerings from food giants like Dole and Chiquita.

For every successful commercial operation in Minnesota, there are dozens of nonprofits, educational institutions, small-scale entrepreneurs, urban farmers and hobbyists growing produce and other plants in greenhouses and grow rooms.

At the Greensted in nearby Zumbrota, workers grow microgreens in a small shed that they sell directly to Lunds & Byerlys. In Tower, a member of the Bois Forte Band of Chippewa left her career as an architect in New York City and returned to northern Minnesota to form Harvest Nation with her sister and daughters.

Harvest Nation is seeking investors to back an aeroponic farm, with a hope to provide better produce options for the tribal community. At one point, founder Denise Pieratos said, there was talk of locating a farm underground in the Soudan Mine, but now they're looking for warehouse space.

"My reservation has twice the rate of diabetes compared to other reservations in the state," Pieratos said. "That's been the big impetus for us to have food grown locally all the year round that everyone can afford, and that we can deliver to them every week."

FACT BOX: Different types of "ponics"

Three related technology systems are used to grow plants indoors without soil, an increasingly common trend in places like Minnesota where it wasn't previously possible to raise leafy vegetables year-round.

Hydroponics: Plants are grown in water that's been treated with nutrients like nitrogen, phosphorous and potassium.

Aeroponics: Plants are grown without soil and not submerged in water but are misted with nutrient-rich water that's continually recycled through the system.

Aquaponics: Plants are grown in water with fish, creating a mutually beneficial environment of fertilizing and cleaning the water in a closed loop.