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United States Department of Agriculture

Agricultural Research Service

Research Project: PROPOSAL TO DEVELOP NEW PLANT HARDINESS MAP DATA FOR THE UNITED STATES

Location: North Central Regional Plant Introduction Station, Ames, Iowa

Title: Horticultural applications of a newly revised USDA Plant Hardiness Zone Map

Authors
item Widrlechner, Mark
item Daly, Christopher -
item Keller, Markus -
item Kaplan, Janet

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2010
Publication Date: February 15, 2012
Citation: Widrlechner, M.P., Daly, C., Keller, M., Kaplan, J.S. 2012. Horticultural applications of a newly revised USDA Plant Hardiness Zone Map. HortTechnology. 22(1):6-19.

Interpretive Summary: The accurate prediction of winter injury caused by low-temperature events is a key component of the effective cultivation of trees, shrubs, vines and herbaceous perennials. A common way to visualize geographic patterns in the severity of low-temperature events is to map a climatological variable that closely corresponds to plant survival. The USDA Plant Hardiness Zone Map (PHZM) is one of the most widely used maps created for that purpose. We present a short history of PHZM development, including the recent production of a new, high-resolution version of the PHZM, and discuss how such maps relate to winter hardiness and to other climatic factors affecting hardiness. The new PHZM is based on extreme minimum temperature data logged annually from 1976-2005 at 7,983 weather stations in the United States, Puerto Rico, and adjacent regions in Canada and Mexico. The PHZM is accessible via an interactive website, which can be applied to a wide range of horticultural applications. For example, we highlight how the PHZM can be used as a tool to evaluate potential vineyard sites in the Pacific Northwest and as a data layer together with moisture-balance data to predict the survival of Yugoslavian woody plants in South Dakota. In addition, the new map includes a zip code finder, and we describe how it may be used by governmental agencies for risk management and the development of recommended plant lists, by horticultural firms to schedule plant shipments, and by other commercial interests that market products seasonally. This information should be of great interest to scientists studying plant adaptation and the effects of extreme low temperatures on plant survival, but will also be of value to horticulturists, gardeners, producers of horticultural commodities, such as tree fruits and nursery crops, and firms that ship and market horticultural products.

Technical Abstract: The accurate prediction of winter injury caused by low-temperature events is a key component of the effective cultivation of woody and herbaceous perennial plants. A common method employed to visualize geographic patterns in the severity of low-temperature events is to map a climatological variable that closely correlates with plant survival. The USDA Plant Hardiness Zone Map (PHZM) is one of the most widely used maps constructed for that purpose. We present a short history of PHZM development, culminating in the recent production of a new, high-resolution version of the PHZM, and discuss how such maps relate to winter hardiness per se and to other climatic factors that affect hardiness. The new PHZM is based on extreme minimum temperature data logged annually from 1976-2005 at 7,983 weather stations in the United States, Puerto Rico, and adjacent regions in Canada and Mexico. The PHZM is accessible via an interactive website, which facilitates a wide range of horticultural applications. For example, we highlight how the PHZM can be used as a tool for site evaluation for vineyards in the Pacific Northwest and as a data layer in conjunction with moisture-balance data to predict the survival of Yugoslavian woody plants in South Dakota. In addition, the new map includes a zip code finder, and we describe how it may be used by governmental agencies for risk management and development of recommended plant lists, by horticultural firms to schedule plant shipments, and by other commercial interests that market products seasonally.

Last Modified: 11/23/2014
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