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UMass and UNH Research Trials

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

Through this research, we are exploring 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?

Low Tunnel Cover Materials:  During the winter of 2010/2011 University Research stations and cooperating farms erected low tunnels consisting of various covers to monitor temperatures and light differences.  Depending on how much protection you want, there are some fairly large differences between treatments that we saw.

Brassica Production:  During the winter of 2011/12, UMass experimented with growing a variety of Brassica crops, with different seeding and transplanting dates. We used Dupont 5131, a heavy duty rowcover, with a 6 mil greenhouse plastic cover. 

Onion Production:  We conducted an overwintering study to assess the characteristics of different varieties of that were fall planted and harvested in early spring.  We used Dupont 5131, a heavy duty rowcover, with a 6 mil greenhouse plastic cover.  Also see the attached pdf for results of UNH low tunnel onion trials.

Low tunnel trials 2012-13, UMass:

  • Variety Trials for Overwintering Onions in New England download pdf
    The goal of the onion trial was to determine which varieties would produce the best quality and highest yield for spring markets. We compared eight onion varieties over two winters and found significant differences in bulb number, size, and weight as well as premature bolting.
  • Effect of Direct Seeding Date on Yield of Overwintered Vegetables in Low Tunnels download pdf
    The goal of this project was to evaluate the effect of different seeding dates on the marketable spring yield of one variety each of carrots, beets, spinach, and kale grown using an overwintering low tunnel system. We found that beets did not produce any marketable yields, regardless of seeding dates. Spinach, kale, and carrots all produced marketable yields, but with no significant differences between dates, except in the case of the earliest and latest seedings of kale. The amount of bolting, however, was found to be significantly correlated to seeding date in the case of carrots, where the earlier dates had the highest number of bolted plants.

Low tunnel trials 2011-13, UNH:

  • Overwintering Onions in Low Tunnels, 2012 and 2013 download pdf
    In 2011-12, seven varieties of onions were planted in Durham, NH at the NH Agricultural Experiment Station (zone 5B) to evaluate the potential for overwintering and early spring harvest. In 2012-13, the study was broadened to include ten varieties in Durham, and two varieties in North Haverhill, NH (zone 4B). In the second year, onions were grown with and without the benefit of protective tunnels.

The Center for Agriculture, Food and the Environment and UMass Extension are equal opportunity providers and employers, United States Department of Agriculture cooperating. Contact your local Extension office for information on disability accommodations. Contact the State Center Director’s Office if you have concerns related to discrimination, 413-545-4800 or see