When snow covers the frozen ground, and most South Dakota farmers have sold or stored their products for the season, the operators of Cedar Creek Gardens are still able to grow vegetables and harvest a lucrative crop.
Located in a remote area southwest of Murdo, about 12 miles south of Interstate 90, the sprawling farm is one of dozens in the state that utilize what are called farm tunnels to extend the planting and growing seasons.
The tunnels are fortified above-ground hoop buildings covered in plastic that capture heat from the sun, creating a greenhouse effect. Many of the tunnels at Cedar Creek are covered with two separated layers of plastic and have fans that circulate warm air between the layers, creating even warmer growing conditions.
The tunnels differ from greenhouses in that crops are grown directly into the soil rather than in raised boxes or beds, and they are watered from the ground up instead of from above.
Cedar Creek is run by Peggy Martin and Bud Manke, who are business partners and good friends. Martin and Manke were some of the first South Dakota farmers to install tunnels after reading about them online in the early 2000s.
“At first, we were just going to grow food for our families,” Martin said. “But it’s become a passion, and they (the tunnels) have helped us grow to what we are now.”
Beyond extending the growing season by up to four months each year, the controlled weather conditions and targeted water use also allow them to produce top-quality, organically grown vegetables.
One-pound tomatoes that are firm, filled with nutrients and free of blemishes. Banana peppers as long as bananas and so crisp they snap. Sweet onions the size of softballs. Kale plants that top 5 feet in height.
Tunnels part of a diversified operation
On their farm, they grow crops on 14 acres, have about 1,400 free-range laying chickens, and Manke raises cattle. The farm is dotted with about a dozen tunnel buildings, the largest of which are up to 14 feet tall, 30 feet wide and 200 feet long.
Martin said the tunnels have enabled them to expand their farm and its output over the past 25 years and help them grow into the largest South Dakota specialty farming operation west of the Missouri River.
Martin, Manke and the farmhands they hire grow a wide variety of seasonal produce, including tomatoes (the primary cash crop) as well as pumpkins, melons, sweet and green onions, red and green peppers, kale, cabbage, broccoli, sugar-snap peas, radishes, lettuce and zucchini.
The foods they grow and raise are sold at area farm stands and farmer’s markets but also through a weekly wholesale business that serves West River grocery stores, restaurants and a buyer’s group.
The tunnels have allowed them to plant vegetables as early as March and maintain growth of some hearty varieties for picking as late as mid-December. The first frost date in their region is typically around Sept. 15, Manke said.
“There can be snow out here in the wintertime and it’s 20 degrees when the sun comes up, but it can be 100 degrees inside the tunnels,” Manke said. “It can actually get too hot sometimes, so we have to be careful and open things up.”
Higher productivity, higher profits
Martin did the math to show how the tunnels can increase productivity and profits.
In a 200-foot tunnel, they can place three rows of 100 tomato plants, each of which can produce 40 pounds of fruit, more than double a typical household tomato plant, she said. At an average of $2.25 per pound, and even with 20 percent waste, that single tunnel can produce $21,600 of tomatoes in a single grow-out.
Rachel Lawton, the South Dakota urban conservationist for the U.S. Department of Agriculture’s Natural Resources Conservation Service, runs the federal program that provides financial assistance to qualified individuals and operations that want to install tunnel farms.
Lawton, based in Sioux Falls, said the tunnels aren’t suitable for high-production farms that raise thousands of bushels of corn, soybeans or wheat. But they work well for specialty crop farmers or backyard gardeners who want to produce a stable, almost year-round crop of vegetables, she said.
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