LINCOLN, N.H. -- Farming is tough during a New Hampshire winter -- unless you're growing icicles.

At the base of Loon Mountain in Lincoln, an ice castle not unlike the frosty palace in the Disney movie "Frozen" is rising from the ground, one icicle at a time. It's one of three ice castles being built by the same company -- the others are in Breckenridge, Colo., and Midway, Utah -- this winter.

Brent Christensen, who now lives in Hawaii, started his Ice Castles company a few years ago after spending several winters building elaborate slides and ice towers for his kids in his backyard in Utah. He initially sprayed water onto wooden frames, only to be left with a tangled mess of splintered wood in spring. The next year, he experimented with blocks of ice, building a small igloo to which he added chunks of snow and ice.

"During that process, I almost accidentally started thinking about icicles," he said. "At first it was just for cosmetics. I thought, 'This will look really cool.' And then, with time, I stumbled on the idea of crisscrossing the icicles, and that's when I found ... you can actually grow them in certain ways."

Eventually, he approached ski areas about building larger structures that could serve as temporary art installations and tourist attractions, and the idea took off. It costs tens of thousands of dollars to build the castles, the largest of which spans about an acre, and visitors pay $8 to $10 to walk through them. About 8,000 people have visited the New Hampshire castle since it opened Dec. 27.

Matt Brown, of Somerville, Mass., who toured the castle last week, said he recently saw "Frozen" and was curious to see how a real ice castle compared to the movie version.

"I obviously knew it wouldn't be quite like that because that's an animated thing, and it's a lot easier to animate things than make them in real life, but I thought it would be an interesting way to spend 30 or 60 minutes," he said. "It's really neat."

The castles will continue growing during the season, until they melt in March. Walls that stand 8 to 20 feet could reach 40 to 60 feet in the next month or so, and icicles placed along the tops of walls will become ceilings. But it takes a lot of work, said Cory Livingood, foreman of the New Hampshire castle's crew.

The process starts in the fall, with the installation of elaborate sprinkler systems. When the weather turns cold, water is sprayed onto metal racks to produce thousands of icicles that are harvested and stuck to the ground around sprinkler heads. The icicles are then drenched in water and, depending on the temperature and wind, grow in various shapes and formations. Over the course of a few weeks, towers, tunnels, archways and caves emerge.

"We're technically farmers," Livingood said. "We grow icicles, we handpick them, harvest them, take them out and hand place them around sprinklers, and then we turn on those sprinklers and they grow more."

There are 58 towers on the Lincoln castle, plus a waterfall and an enclosed slide. At night, the castles are lit by colour-changing LED lights embedded in the ice. Sara Bookin-Weiner, also of Somerville, said she appreciates the beauty of the ice at a time of year when "things are so dead and dark."

"Especially now that the holidays are over, in the Northeast we're looking forward to lots of months of blah, and it's really wonderful to have something so creative and artistic and delightful," she said.

Christensen, who also runs a small-engine repair business, said there's a significant amount of mechanical work and engineering involved in designing the castles and setting them up. But Mother Nature handles the artistic side.

"The real artistic part isn't done by us. When you spray water in the middle of the night, and you have icicles that catch the water, that's when the art happens," he said.

Christensen has been in Utah overseeing the project there this winter but will head home to Hawaii soon. He laughed when asked if he'll miss the ice.

"I think about it a lot, but I don't long for it by any stretch," he said.