ELGIN, MINN. – The closest a Minnesotan can get to an invincible summer might be found inside Pam Benike's insulated hoop barn near Rochester.

Inside the barn, which stretches the length of a hockey rink, grow green vegetables — red spinach, Bok choy, radishes — while a balmy 65 degrees or more prevails. On frigid nights, the thin parallel rows are covered with white plastic tarps. The nose-tingling aroma of summer hovers as the only sound is the slow drip from an elevated drainage pipe.

"This is how we grow vegetables up here," said Benike, who runs Prairie Hollow Farm with her family. There's no artificial heating, just insulated plastic walls and sunshine. "The ground is a heat sink."

Benike bent down to put her forefinger into the soil. Just outside, the temperature was subzero. A bright sun beat down. The 52-degree dirt allows her to grow cool season vegetables she sells all over Minnesota, including the Mill City Farmers Market in downtown Minneapolis.

"Take care of the soil, and it'll always take care of you," she said, repeating a line her grandfather used to tell her.

Most northland farmers fill grain bins with harvest in the fall and end fieldwork in the frigid winter. Maybe the dairy operator outside Milaca milks cows, cold temperatures visible in cows' exhaust. The cattle rancher west of Luverne brings hay to her herd.

But a number of Minnesota agriculturalists stay busy in their fields. According to the U.S. Department of Agriculture quinquennial census, revenue from produce in Minnesota "grown under glass or other protection" doubled from $13 million in 2012 to $26 million in 2017.

To grow green plants for food in the frozen ground of Minnesota is a hardy business — and still a rare endeavor. A coterie of greenhouses — veteran hydroponics and aeroponics companies — raise fresh greens in Minnesota's dormant months. And there are places like Prairie Hollow Farm, where insulated hoop barns allow farming on plain old Minnesota soil.

But for customers seeking real, locally raised food, this year-round bounty is treasured.

In downtown St. Paul on the last Saturday in January, farmers market attendees gathered in single-digit temperatures around a fire pit, roasting bratwursts and sipping on complimentary cider. Organizers say it's the coldest outdoor market in North America.

"I can pretty much park, like, 2 feet away," said Cindy Dahl, of St. Paul, who was hustling through the market in brown boots and a stocking cap. She'd bought a bag of meat and eggs.

The fare on Saturday is not as flush as in summer months, when early summer asparagus cedes to midsummer berries and, eventually, September squash. The vibe in July is leisurely, even languid. In January, it can feel like speed skating.

But organizers say hundreds still descend to St. Paul's Lowertown neighborhood every week for the two dozen or so vendors who show up. One grower stood in a snowsuit in the back of a truck. Another stuffed heating pads into her mittens. Susan Brown, chocolatier at Mademoiselle Miel, handed out some honey-ginger tonic.

"It's honey from our rooftop hives, fresh-squeezed lemon and ginger, that's it," Brown said.

For many Minnesota farmers who seek markets year-round, the demand from customers who want local in January is equally symbiotic. Down Hwy. 52, on the outskirts of Zumbrota, a friendly white shed houses an ad-hoc farm store, the Greensted, that carries foods from within 200 miles.

"If you look around, you have to go to Rochester or Northfield or the Cities, so we consider this something of a food desert," said Dean Bredlau, who co-owns the Greensted with his wife, Jayne. "So we invited all our farmers market friends to our retail."

In the back hums the hose, as employees wash down trays carrying microgreens, or tiny sprouts the couple grows indoors and sells to retailers and farmers market customers.

"We are harvesting these right when they are starting to photosynthesize," Dean Bredlau said. He plucks the greens from trays labeled "kale" and "red giant mustard" and pops them into his mouth.

Dean Bredlau worked in the food industry at a honey plant in Cannon Falls, Minn. Jayne Bredlau worked in hospitality at Rochester's Kahler Grand Hotel. A favorite with customers is the Wacky Salad, a bagged salad.

"A little guy was in here and asked, 'Do you have Doritos?'" Jayne Bredlau said. "I told him, 'No, but we do have organic corn tortilla chips.'"

The state's biggest farmers have more free time in winter to attend farm association conferences and legislative updates, like the one held two weeks ago in Pierz.

But for the region's smallest farmers, those who winter-store potatoes and onions and carrots, demand can actually pick up in the winter.

"We grow more in the summer, but [patrons] say, 'Oh, it's too hot to cook,' or 'We're going out of town on vacation,'" said Aimee McAdams, who runs Northwood Mushrooms with her husband, Jeremy, outside Clayton, Wis. "We sell more in the winter or fall, when people are ready to cook."

The McAdamses utilize indoor growing chambers for the mushrooms to fruit year-round. They used to live in Minneapolis and would transport logs — which mushrooms grow on — to backyards across south Minneapolis until a neighbor complained.

"They said we looked like the Ozarks, and I was like, 'What's wrong with the Ozarks?'" Aimee McAdams said.

Now, a little over an hour northeast from the Twin Cities, they trek to the (indoor) winter market at Mill City in downtown Minneapolis.

With the busiest summer markets still months away, some patrons lingered, looking to grasp onto that bolt of fresh food and talk with the farmers, on a recent Saturday.

Outside, exhaust poured from the tailpipe of a van, while vendors loaded up vegetables —the bright color of apples, a smack of color in the middle of an otherwise white-and-gray day.