Producers of horticultural crops in the United States, and the research and extension specialists who assist them, are increasingly recognizing high tunnels as valuable tools to assist with season extension and crop protection. High tunnels are also sometimes called hoop houses or unheated greenhouses and they include a range of designs from single-span to multi-span structures that are usually covered with a single layer of 6-mil polyethylene greenhouse film. High tunnels may be constructed to be semipermanent, movable, or temporary, although they are usually considered temporary structures for purposes of property assessment and taxation (Blomgren and Frisch, 2007). Typically, high tunnels are unheated and are passively ventilated, but they must have water for irrigation, and are used to produce a wide variety of crops directly in the soil, or less frequently, in artificial media (Lamont et al., 2003; Heidenreich et al., 2008). In regions with winter snow and ice, the polyethylene film is generally removed from multi-span high tunnels during the winter months, while it is usually left on single-span tunnels, which are often used for the production of winter crops (Blomgren and Frisch, 2007).
Despite having been invented in the United States (Emmert, 1955), high tunnels have not been adopted as quickly by fruit, vegetable, and flower growers here as in many other countries (Wittwer, 1993). While high tunnels or overwintering structures have been widely used in the nursery industry, it was not until the early 1990s that research and extension professionals in the Northeast began to report the high potential of these structures for vegetable production (Wells and Loy, 1993), initially reporting their great advantage for early production of warm season crops such as tomato (Solanum lycopersicum). Multiple efforts, many by innovative growers (Blomgren and Frisch, 2007; Byczynski, 2003; Coleman, 1998, 1999; Wiediger and Wiediger, 2003), have contributed to today's increasing awareness of the potential value of high tunnels for early or extended season production of fruit, vegetable, and flowers of outstanding quality. Because of their low construction and operating costs, it is common for producers to recover their investment within 1 or 2 years (Blomgren and Frisch, 2007).
Today, the use of high tunnels is increasing rapidly in many places in the United States. There are many examples of research and extension programming and education resources being developed around the United States. (Jett, 2004; Jimenez et al., 2005; Lamont et al., 2002, 2005; Nennich et al., 2004). Information on the Internet about high tunnels and their uses has burgeoned over the past decade. Several universities, agencies, and businesses have published digital information about high tunnel construction and use. One university-sponsored website (Kansas State University, 2003) contains original content geared for grower and educator audiences, as well as links to other websites of interest. This website also provides access to an e-mail listserv that is widely used by growers, allied industry, and academics to ask questions and exchange information related to high tunnel use (Kansas State University, 2004).
To attempt to capture a snapshot of current high tunnel use nationwide, we conducted an informal survey of state extension specialists at land grant universities. We present the results of the survey in this article to highlight the growing body of high tunnel research, extension education, and usage by growers in the United States.
Blomgren, T. & Frisch, T. 2007 High tunnels: Using low-cost technology to increase yields, improve quality and extend the season 27 Jan. 2008 <http://www.uvm.edu/sustainableagriculture/hightunnels.html>.
Both, A.J., Reiss, E., Sudal, J.F., Holmstrom, K.E., Wyenandt, C.A., Kline, W.L. & Garrison, S.A. 2007 Evaluation of a manual energy curtain for tomato production in high tunnels HortTechnology 17 467 472
Heidenreich, C., Pritts, M., Kelly, M.J. & Demchak, K. 2008 High tunnel raspberries and blackberries Cornell Univ. Dept. Hort. Publ. No.47 12 June 2008 <http://www.ces.ncsu.edu/depts/hort/greenhouse_veg/pdf/hightunnels.brambles.pdf>.
Kansas State University 2004 High tunnel discussion listserv archives 3 Mar. 2008 <http://listserv.ksu.edu/archives/hightunnels.html>.
Jimenez, D., Walser, R. & Torres, R. 2005 Hoop house construction for New Mexico: 12-ft. × 40-ft hoop house Univ. New Mexico Coop. Ext. Serv. Circ. 606 27 Jan. 2008 <http://cahe.nmsu.edu/pubs/_circulars/CR-606.pdf>.
Kadir, S., Carey, E.E. & Ennahli, S. 2006 Growth, yield and fruit quality of two strawberry cultivars (Fragaria ×ananassa Duch.) under high tunnel compared with field conditions HortScience 41 329 335
Knewtson, S. & Carey, E. 2007 Soil quality in high tunnels: Producer perception and reality in the central Great Plains HortScience 42 899 (Abstr.).
Lamont, W.J., Orzolek, M.D., Jay Holcomb, E., Demchak, K., Burkhart, E., White, L. & Dye, B. 2003 Production system for horticultural crops grown in Penn State high tunnel HortTechnology 13 358 362
Lamont, W.J., Orzolek, M.D., Rasmussen, C. & White, L. 2005 High tunnel production manual 2nd ed Pennsylvania State Univ. Dept. of Hort. Ext. Publ. High Tunnel Ser. 1
Lamont, W.J., Orzolek, M.D., Demchak, K., Jay Holcomb, E., Crassweller, R.M., Burkhart, E., White, L. & Dye, B. 2002 Penn State high tunnel extension program HortTechnology 12 732 735
Miles, C. & Labine, P. 1997 Portable field hoophouse Washington State Univ. Ext. Publ. EB1825 3 Mar. 2008 <http://cru.cahe.wsu.edu/CEPublications/eb1825/eb1825.html>.
Nennich, T.T., Wildung, D. & Johnson, P. 2004 Minnesota high tunnel production manual for commercial growers Univ. Minnesota Ext. Serv. M1218 27 Jan. 2008 <http://www.extension.umn.edu/distribution/horticulture/M1218.html>.
Orzolek, M.D., Lamont, W.J. & White, L. 2004 Promising horticultural crops for production in high tunnels in the mid-Atlantic area of the United States Acta Hort. 633 453 458
Reiss, E., Both, A.J., Garrison, S., Kline, W. & Sudal, J. 2004 Season extension for tomato production using high tunnels Acta Hort. 659 153 160
Spaw, M. & Williams, K.A. 2004 Full Moon Farm builds high tunnels: A case study in site planning for crop production structures HortTechnology 14 449 454
U.S. Department of Agriculture 2007 United States 2007 census of agriculture Natl. Agr. Stat. Serv. form no. 07-A0201 13 June 2008 <http://www.agcensus.usda.gov/publications/2007/index.asp>.
Wells, O.S. & Loy, J.B. 1993 Rowcovers and high tunnels enhance crop production in the northeastern United States HortTechnology 3 92 95
Wright, B. 2005 The unfrozen tundra: Extending the growing season in Wisconsin 25 Feb. 2008 <http://www.co.brown.wi.us/UW_Extension/CommGardens/High%20Tunnels.pdf>.
Zhao, X., Iwamoto, T. & Carey, E. 2007 Antioxidant capacity of leafy vegetables as affected by high tunnel environment, fertilization, and growth stage J. Sci. Food Agr. 87 2692 2699