USDA Maps Out New Plant Hardiness Zones

New USDA Cold Hardiness Zone map

The USDA has released the new version of its Plant Hardiness Zone Map (PHZM), updating a useful tool for gardeners and researchers for the first time since 1990 with greater accuracy and detail. The new map—jointly developed by USDA’s Agricultural Research Service (ARS) and Oregon State University’s (OSU) PRISM Climate Group—is available online at www.planthardiness.ars.usda.gov

For the first time, the new map offers a Geographic Information System (GIS)-based interactive format and is specifically designed to be Internet-friendly. The map website also incorporates a “find your zone by ZIP code” function. Static images of national, regional and state maps also have been included to ensure the map is readily accessible to those who lack broadband Internet access.

“This is the most sophisticated Plant Hardiness Zone Map yet for the United States,” said Catherine Woteki, USDA Under Secretary for Research, Education and Economics. “The increases in accuracy and detail that this map represents will be extremely useful for gardeners and researchers.”

Plant hardiness zone designations represent the average annual extreme minimum temperatures at a given location during a particular time period. They do not reflect the coldest it has ever been or ever will be at a specific location, but simply the average lowest winter temperature for the location over a specified time. Low temperature during the winter is a crucial factor in the survival of plants at specific locations.

The new version of the map includes 13 zones, with the addition for the first time of zones 12 (50°F to 60°F) and 13 (60°F to 70°F). Each zone is a 10°F band, further divided into 5°F Fahrenheit zones “A” and “B.”

To help develop the new map, USDA and OSU requested that horticultural and climatic experts review the zones in their geographic area, and trial versions of the new map were revised based on their expert input.

Compared to the 1990 version, zone boundaries in this edition of the map have shifted in many areas. The new map is generally one 5°F half-zone warmer than the previous map throughout much of the United States. This is mostly a result of using temperature data from a longer and more recent time period; the new map uses data measured at weather stations during the 30-year period 1976-2005. In contrast, the 1990 map was based on temperature data from only a 13-year period of 1974-1986.

However, some of the changes in the zones are a result of new, more sophisticated methods for mapping zones between weather stations. These include algorithms that considered for the first time such factors as changes in elevation, nearness to large bodies of water, and position on the terrain, such as valley bottoms and ridge tops. Also, the new map used temperature data from many more stations than did the 1990 map. These advances greatly improved the accuracy and detail of the map, especially in mountainous regions of the western U.S. In some cases, they resulted in changes to cooler, rather than warmer, zones.

While about 80 million American gardeners, as well as those who grow and breed plants, are the largest users of the USDA Plant Hardiness Zone Map, many others need this hardiness zone information. For example, the USDA Risk Management Agency uses the USDA plant hardiness zone designations to set some crop insurance standards. Scientists use the plant hardiness zones as a data layer in many research models such as modeling the spread of exotic weeds and insects.

Although a poster-sized version of this map will not be available for purchase from the government as in the past, anyone may download the map free of charge from the Internet onto their personal computer and print copies of the map as needed.

Leave a Reply

Featured Stories
Judi Whitson, 2016 Florida Woman of the Year in Agriculture
Citrus
April 24, 2017
Who Will Be Florida’s next Woman of the Year in Agriculture?
Nomination period now open for longstanding recognition from FDACS. Read More
Apples & Pears
April 24, 2017
Researcher Uncovers the Origins of ‘Honeycrisp’ Apple
Thanks to the scientific data available through gene sequencing, a graduate student unlocks the mystery parentage. Read More
Citrus
April 23, 2017
Bio Huma Netics, Inc., and Mesa Verde Resources Expand Product Selection
Strategic alliance between the two companies is designed to offer customers greater access to products. Read More
GenNext Growers
April 22, 2017
Next Generation of Leaders Gets Yearlong Almond Immersion
Almond Leadership Program enters its ninth year with the 2017 class. Read More
Washington Capitol building
Citrus
April 21, 2017
Alliance Stepping Up Efforts to Protect Specialty Crops
The Specialty Crop Farm Bill Alliance has kicked off its efforts to communicate to Congress its priority needs for the Read More
glass of red wine
Grapes
April 20, 2017
Would You Be Willing to Pay More for Organic Wine?
While consumers might be ready to fork over more for organic produce, study says the feeling isn't quite the same when it comes to the adult beverage. Read More
UF/IFAS scientist Jonathan Crane inspects avocado trees in South Florida
Crop Protection
April 20, 2017
Beetle Battle Burgeoning for South Florida Avocado Growers
Scientists identify more species of pests that vector deadly fungus. Read More
farm labor pic for web
Citrus
April 20, 2017
Farm Labor Is in Crisis
To have a great crop potentially rot in the field because workers can’t be sourced is probably worse than a weather event taking out production. Read More
Zellwood, FL, muck farming history photo
Vegetables
April 19, 2017
Free Forum to Hail Florida Muck Farming History
Zellwood Historical Society helping shine a light on an industry that defined the area. Read More
Vegetables
April 19, 2017
Want Low Drama Food Safety Inspections? Embrace Paperwork [Opinion]
When I was in high school, my mom was the administrator of an outpatient hospital. Like all hospitals, Mom’s was Read More
Vegetables
April 19, 2017
Which Vegetable Crops Are the Most Popular?
The editors at American Vegetable Grower asked growers about their crops as part of our 2017 State of the Vegetable Industry survey, and gained a lot of insight into which crops are most commonly grown, and how well those crops are performing. Read More
Grapes
April 19, 2017
Donnell Brown Named President of National Grape & Wine Initiative
New president brings experience in wine industry communications. Read More
Alternaria Leaf Spot of Cucurbits
Cucurbits
April 19, 2017
Alternaria Leaf Spot Awareness Can Save Your Cucurbit Crops
Learn how to identify, the survival and spread, as well as management methods for this malady. Read More
Apples & Pears
April 19, 2017
Young Apple Growers Meet with Lawmakers
Apple leaders from across the country discuss ag issues such as labor, trade, and research. Read More
Barnes Farm cabbage field in Hastings, FL
Citrus
April 18, 2017
Florida Growers Seeking Inspiration Need Not Look Far
The firsthand experience of speaking with farmers and actually seeing all the hard work, knowledge, ingenuity, and people behind where our food comes from is invaluable. Read More
The Latest
Citrus
April 24, 2017
Who Will Be Florida’s next Woman of the …
Nomination period now open for longstanding recognition from FDACS. Read More
Apples & Pears
April 24, 2017
Researcher Uncovers the Origins of ‘Hone…
Thanks to the scientific data available through gene sequencing, a graduate student unlocks the mystery parentage. Read More
Citrus
April 23, 2017
Bio Huma Netics, Inc., and Mesa Verde Re…
Strategic alliance between the two companies is designed to offer customers greater access to products. Read More
GenNext Growers
April 22, 2017
Next Generation of Leaders Gets Yearlong…
Almond Leadership Program enters its ninth year with the 2017 class. Read More
Citrus
April 21, 2017
Alliance Stepping Up Efforts to Protect …
The Specialty Crop Farm Bill Alliance has kicked off its efforts to communicate to Congress its priority needs for the Read More
Apples & Pears
April 21, 2017
Interpera Congress Heads to Pacific Nort…
International pear conference comes to the U.S. for the first time. Read More
Grapes
April 20, 2017
Would You Be Willing to Pay More for Org…
While consumers might be ready to fork over more for organic produce, study says the feeling isn't quite the same when it comes to the adult beverage. Read More
Crop Protection
April 20, 2017
Beetle Battle Burgeoning for South Flori…
Scientists identify more species of pests that vector deadly fungus. Read More
Citrus
April 20, 2017
Farm Labor Is in Crisis
To have a great crop potentially rot in the field because workers can’t be sourced is probably worse than a weather event taking out production. Read More
Vegetables
April 19, 2017
Free Forum to Hail Florida Muck Farming …
Zellwood Historical Society helping shine a light on an industry that defined the area. Read More
Vegetables
April 19, 2017
Want Low Drama Food Safety Inspections? …
When I was in high school, my mom was the administrator of an outpatient hospital. Like all hospitals, Mom’s was Read More
Vegetables
April 19, 2017
Which Vegetable Crops Are the Most Popul…
The editors at American Vegetable Grower asked growers about their crops as part of our 2017 State of the Vegetable Industry survey, and gained a lot of insight into which crops are most commonly grown, and how well those crops are performing. Read More
Grapes
April 19, 2017
Donnell Brown Named President of Nationa…
New president brings experience in wine industry communications. Read More
Cucurbits
April 19, 2017
Alternaria Leaf Spot Awareness Can Save …
Learn how to identify, the survival and spread, as well as management methods for this malady. Read More
Apples & Pears
April 19, 2017
Young Apple Growers Meet with Lawmakers
Apple leaders from across the country discuss ag issues such as labor, trade, and research. Read More
Citrus
April 18, 2017
Florida Growers Seeking Inspiration Need…
The firsthand experience of speaking with farmers and actually seeing all the hard work, knowledge, ingenuity, and people behind where our food comes from is invaluable. Read More
Citrus
April 18, 2017
Citrus Growth Path Uncertain as Florida …
According to the latest Lay of the Land Market Report, the waiting game for a solution to greening has tempered groves sales. Read More
Farm Management
April 18, 2017
Survey Says New York Growers Lost More t…
Growers say they suffered more than 50% crop losses in Western New York. Read More