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Alaska Growers Net Many Benefits from Seasonal High Tunnel

Posted by Dave Ianson, Palmer (Alaska) Soil and Water Conservation District in Conservation Food and Nutrition Farming
Feb 21, 2017
A high tunnel like this one in Alaska’s Matanuska-Susitna Valley lengthen the growing season for Alaska farmers.
A high tunnel like this one in Alaska’s Matanuska-Susitna Valley lengthen the growing season for Alaska farmers.

Seasonal high tunnels have lots of benefits, especially in a state like Alaska where cold weather leaves a short growing season. They are incredible garden heaters, season extenders and profit generating machines for Alaska growers.

Seasonal high tunnels allow farmers like Alex and Kelly Strawn in Lazy Mountain, part of Alaska’s Matanuska Valley, to save on energy costs, control where to put water and fertilizer and grow more variety of vegetables for a longer period of time.

Because of these benefits, USDA’s Natural Resources Conservation Service (NRCS) provides assistance to farmers wanting to build a high tunnel.

While high tunnels may look like greenhouses, growers manage them quite differently. In high tunnels, plants are grown directly in the ground.  High tunnels don’t use heaters and lights. Opening and closing the high tunnel regulates the sun’s heat.

High tunnels also control the rain. In Alaska, rains often come during the best time to harvest. High tunnels serve as an umbrella, minimizing rain damage to valuable crops.

Their warmth enables the production of warm-season crops such as peppers, tomatoes, cucumbers and melons, which do not grow well outdoors in Alaska. “These warm-season crops are customer favorites and bring premium prices at the farmer’s market,” Kelly Strawn said. Last year, the Strawns grew three varieties of peppers, sweet corn and artichokes in their high tunnel.

High tunnels extend the growing season by allowing the grower to plant several weeks earlier in the spring and harvest well beyond the traditional time when plants are typically killed by frost.

Farmers growing leafy greens and other fast-growing produce have enough time to grow two crops, doubling their yields. The lengthened season of the high tunnel also enables Alaska growers to raise some of the more flavorful, mid-season varieties that will not ordinarily mature in Alaska’s short season.

The Strawns were some of the first people in the Matanuska-Susitna Valley to build a high tunnel with the help of NRCS.

As high tunnel veterans now, the Strawns have some advice. First, make sure the high tunnel can be ventilated. Tunnels with automatic ventilation are best, they said.

Also, make sure to space out plants to allow for air movement. This reduces humidity and stagnant air, which can increase fungal molds on plants.

The Strawns also recommend intercropping plant species, meaning mix the plants in an area. An example is intercropping tomatoes with certain plants because tomatoes produce a volatile alkaloid called solanine that acts as a natural pesticide.

They also recommend growers to take advantage of their watering system. The Strawns mounted their water tank inside the high tunnel to serve as a “heat sink,” which increases heat at night. In addition, they mounded soil in raised beds and buried their irrigation to keep in heat during cooler times.

Learn more about NRCS assistance for seasonal high tunnels.