Low Tunnels

UMass, UNH and cooperating farms take a look at how these low cost structures can be integrated into a winter production system.

Low tunnels have been shown to provide sufficient winter protection for fall-planted extremely hardy crops to survive and speed up spring harvest by 4-5 weeks (Coleman 2009).  These simple structures serve as a cost-effective strategy for filling the March to May gap in vegetable harvest.  Low tunnels are temporary, unheated structures 4-8 ft tall, 5-10 ft wide with hoops made of conduit (plastic or metal), covered with spunbonded rowcover, and/or plastic.

While they afford less winter protection and are inaccessible after snowfall, low tunnels with quick hoops can be erected for $0.50-$1.00 per square foot, estimated to be 5% of the cost of a 4-season greenhouse (Coleman 2009) or 15-30% of the cost of an unheated tunnel (Sideman). They offer the advantage of being easily moved, allowing rotation of winter production areas.  In New England, low tunnel are primarily used for prolonging the fall harvest season until just prior to snowfall. Many farmers have found that low tunnels can also work for overwintering crops of the Brassica, allium, Chenopodia and umbel families (Coleman 2009, OHare 2006).

Research undertaken by this project will explore some of the many questions regarding overwintering crops in low tunnels: Which crops and varieties are adapted for this purpose? What amount of protection can we expect from low tunnels constructed of different materials? What are the planting dates that maximize spring production? How are they best managed in spring? Is production in low tunnels cost-effective and practical?

During the winter of 2010/2011 University Reserach stations and cooperating farms erected low tunnels consiting of various covers to monitor temperatures and light differences. Results!  Follow this link for some resutls from our 2010/2011 trials.  Depending on how much protection you want, there are some fairly large differences between treatments that we saw.

2012 Tunnels are Up!

For 2012, we are experimenting with growing three types of  brassica greens including Siberian Kale,  Brassica napa, Mizuna-Tatsoi-Maruba cross, Brassica rapa and Mixed Mustard greens, Brassica juncea with plant date as a treatment.  In seperate tunnels we are conducting an overwintering study to assess the characterisics of different varities of spinach and onions that are fall planted with the intent of being harvested in the late winter or early spring.  For all tunnels we choose a covering that gave us the most protection on the coldest day/night of 2011.  We are using Dupont 5131 heavy duty rowcover with a 6 mil greenhouse plastic cover.  Temperatures inside and outside of the tunnels are being logged every hour and the plants inside are still continuing to grow.  Just peaking through the covers you can see obvious differences between varities.

See links below for more details on experimental design including plant dates and varities being grown.