High tunnels are being discussed a lot lately in farm and garden circles in Alaska, but what are high tunnels and why are they so popular in Alaska?
Basically, a high tunnel is a plastic-covered growing area without a supplemental heating system that is at least 6 feet high at the peak. High tunnels can be large enough to drive farm equipment through and plants are grown directly in the ground. This is in contrast to many greenhouses, which are permanent structures that often have raised beds with imported soil and supplemental heat.
High tunnel popularity has to do with how warm they are inside, which allows Alaskans to start growing plants in them a month earlier and then a month longer than we can outdoors in a typical garden. So, instead of having fresh lettuce three months of the year, you can have it for five. There are hundreds of new high tunnels throughout Alaska and hundreds more planned for next year. What’s not to love? You can plant almost anything in a high tunnel such as vegetables, fruits, trees, flowers, etc.
As more people have begun using high tunnels, agriculture and horticulture Extension agents are now getting lots of questions about them. Because of that, we felt there was a need for the eight Extension agents statewide to learn enough about high tunnels to help you. In order to do that, we had a workshop earlier this month in Kenai especially for Extension personnel and our partners at soil and water conservation districts, who answer questions for people who have high tunnels.
So, what did we learn? First, the Natural Resources Conservation Service (NRCS) has a cost-share program that might be able to help reduce your starting expenses. If you have a garden area that you want to cover with a high tunnel to make it more productive, the NRCS program may be right for you, but be prepared to do some paperwork. Second, plant growth inside a high tunnel can be amazing, but be ready to intensively manage your soils, watering and plants differently.
Here are some high points of what was learned at the high tunnel workshop:
· Pay attention to the temperature in the high tunnel. If it gets too hot or too cool, you may lose plants. Sides of high tunnels can be raised to allow more airflow or fans can be installed to turn on automatically. Floating row covers can be used inside the high tunnel for additional plant protection when the temperature drops.
· Because the plants are under cover, you have to supply the water. If your water is too salty, your soil may degrade over time. Happily, in the winter you can remove the plastic cover and your melting snow can wash out the salts.
· Be careful of your soil fertility. Fast-growing plants use a lot of nutrients so be sure to get your soil tested regularly.
· There are insects and diseases that will become more of a problem inside the high tunnel than outside. Learn what these are and look for them so you can control them early.
· Make sure your high tunnel is designed to be strong enough to handle the snow and wind in your area. Some people choose to remove the plastic covering during the winter to eliminate snow and wind issues; others choose to manually remove snow throughout the winter.
As you all know, there is a surprising amount of things you need to know to grow plants. If you really want to be good at growing plants and desire to do it sustainably and, perhaps, make a business of it, be prepared to study and learn from others. Your agriculture and horticulture Extension agents throughout our great state of Alaska can now help you better if you have specific questions about high tunnels. For general information, please visit http://bit.ly/nrcshightunnels.
Steven Seefeldt is the Tanana District agriculture and horticulture agent for the Cooperative Extension Service, a part of the University of Alaska Fairbanks, working in cooperation with the U.S. Department of Agriculture. He can be reached at 907-474-2423 or firstname.lastname@example.org.