Minimally Heated High Tunnel For Winter Vegetable Production in Upper Midwest

Commodities

Practices

The main problem this project addresses is the question of is it economically feasible to use the combination of a high tunnel, row covers, convective tubing and a heater to produce high value and high demand cold tolerant crops even in the dead of winter in Southern Minnesota. We've observed other growers in other parts of the country and even in Canada utilizing this strategy to grow crops all year round but we haven't seen this widely adopted in Minnesota.

If it is economically feasible to do this, which this grant will explore, then it will help solve subsequent problems for farmers. Specifically, on our farm the two problems it would solve would be the improvement of winter cash flow and the ability to hire year round employees. Together, solving these problems would make our farm more resilient by having more reliable workers and more reliable winter cash flow. Further, it would help with customer retention as we wouldn't need to reestablish contact with customers each spring.

My solution to the problem of economically producing fresh produce through a southern Minnesota winter is to use our existing high tunnel with double layer plastic, a high efficiency furnace, row cover & convection tubing coupled with cold hardy and high demand crops like lettuce, spinach, bok choy, scallions, kale & radish to offer fresh produce during the winter months.

Our experience growing in an unheated tunnel has taught us that crops like spinach & some varieties of lettuce can be overwintered without supplemental heat. However, cold snaps and unpredictable weather can make this unreliable. We hypothesize that the use of row cover with convective heat tubing underneath and a high efficiency furnace will allow us to produce these crops in an economically feasible manner while utilizing existing infrastructure on our farm.

The setup will include using a high tunnel with double layer poly for enhanced insulation as the main infrastructure the analysis will be conducted in. Inside the tunnel we will use steel conduit to create two hoops over 3 or 4 beds (7 total beds inside the tunnel) inside the tunnel. You can think of it as a tunnel inside a tunnel. Then, we'll use convective tubing to direct warm air from a high efficiency propane furnace to the space underneath the row cover. That way, we're only heating the space under the row cover and we're only heating that space to approximately 30* Fahrenheit.

We will then complete an enterprise analysis to look at the labor and total costs involved in this production method to see if it's economically feasible. Labor involved will include bed preparation, planting, crop care including management of the row cover, harvest & wash/pack. Materials involved will include seeds, fertilizer, conduit, row cover, thermostats, sensors & convective tubing. Fuel costs will include propane and electricity for thermostats and monitoring equipment. Additional costs would include depreciation of the high tunnel and equipment used.