Extending the Growing Season
High Tunnels Use and Farm to School in the Upper Midwest
The Upper Midwestern states of Minnesota, Iowa and Wisconsin are simultaneously known for their cold winters and their high agriculture production. Like many states in the country, these states are experiencing increased interest in local and regional food procurement, particularly from institutions such as schools, childcare centers, universities and hospitals. While many farms in the Upper Midwest only produce during the typical growing season of mid-May through early October,1 the use of technology and practices to extend the growing season is rising, in part as a response to the increased demand for local and regional fruit and vegetables. This report focuses on the current use of season extension technology and practices in the Upper Midwest and particularly the use of high tunnels and hoop houses identifies potential strategic pathways for ramping up season-extending production of fruits and vegetables in the region to meet growing demand, particularly in the K-12 market.
Overview of Season Extension Technologies and Practices
Season extension technologies and practices span a wide range of options that can be adapted to the needs of individual farms. The purpose of season extension is to modify agriculture micro-climates to provide enhanced growing conditions beyond the typical growing season of the region. According to the National Sustainable Agriculture Information Service, such technologies and practices are divided into two categories—cultural practices and “plasticulture” practices (i.e. use of plastic technology). Cultural practices can modify growing conditions with or without additional infrastructure and may include: irrigation, “smudge pot” heaters and/or wind machines; wind breaks, cultivar selection, shade, transplanting, multiple cropping and other practices such as mulching. Plasticulture practices, in their use of manufactured products, usually require infrastructure and may include: plastic film mulches, drip irrigation tape, row covers low tunnels and high tunnels.2 Traditional greenhouses, as well as hydroponic and aquaculture operations, are also a form of season extension, as they create highly managed growing environments for year-round production. Regardless of the form, multiple season extension technologies and practices are often implemented simultaneously or in coordination on a farm to maximize productivity.
Within the range of options, this report specifically addresses the use of high tunnels—also known as hoop houses or passive solar greenhouses—amongst small- to medium-scale specialty crop farmers in the Upper Midwest of the United States. This particular season extension technology and set of practices is a common, inexpensive option for Upper Midwestern farmers interested in extending their growing season.