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
FruitsStudy: Stink Bugs Track Favorite Fruits Through Growing Season
July 7, 2015
The brown marmorated stink bug has a bad reputation. And for good reason: every summer, this pest attacks crops causing Read More
FruitsNew Research Shows Spotted Wing Drosophila Repellent Naturally Produced In Fruits
July 7, 2015
Spotted wing drosophila, Drosophila suzukii, is a big pest for fruit growers. However, Christine Krause Pham and Anandasankar Ray, researchers Read More
CitrusNew York Representative Introduces Bill To Help Young Growers
July 7, 2015
The Young Farmer Success Act of 2015 was recently introduced by U.S. Rep. Chris Gibson, R-NY, and  U.S. Rep. Joe Read More
Farm ManagementGenNext Growers Taking Marketing To The Next Level
July 7, 2015
In part two of our Marketing Tips From 14 GenNext Growers feature, we conclude with the remaining marketing and branding Read More
money
Insect & Disease Update$1 Million Citrus Greening Research Project Gets Green Light
July 7, 2015
Funding approved in Florida's state budget to bolster development of beneficial bacteria-infused product. Read More
PotatoesNominations Open To Fill Board Seats For U.S. Potato Board’s 2016-2019 Term
July 7, 2015
Fifty-four board members will be elected or re-elected to fill open seats on the United States Potato Board. Read More
More VegetablesGeorgia Court Tells Vidalia Onion Growers When They Can Pick Their Crop
July 7, 2015
Concern was over the brand being hurt by shipping poor quality crops too soon in the season. Read More
Agritainment
CitrusAgritourism Gaining Lots Of Ground In Sunshine State
July 6, 2015
Researchers report more farming operations are growing revenue by hosting festivals, tours, wine tastings, and more. Read More
Photo of New Guinea flatworm found near Coral Gables, FL
CitrusSouth Florida’s Newest Pest Has Significant Ooze Factor
July 2, 2015
The infamous New Guinea flatworm, one of the ‘world's worst invasive alien species,’ might have found a new home. Read More
Farm ManagementPMA Advocates For Improvements To Proposed FSMA Mandatory Food Recall Guidance
July 2, 2015
This week the Produce Marketing Association (PMA) submitted comments on behalf of its membership to FDA regarding the proposed Mandatory Read More
The Latest
FruitsStudy: Stink Bugs Track Favorite Fruits Through Growing…
July 7, 2015
The brown marmorated stink bug has a bad reputation. And for good reason: every summer, this pest attacks crops causing Read More
FruitsNew Research Shows Spotted Wing Drosophila Repellent Na…
July 7, 2015
Spotted wing drosophila, Drosophila suzukii, is a big pest for fruit growers. However, Christine Krause Pham and Anandasankar Ray, researchers Read More
CitrusNew York Representative Introduces Bill To Help Young G…
July 7, 2015
The Young Farmer Success Act of 2015 was recently introduced by U.S. Rep. Chris Gibson, R-NY, and  U.S. Rep. Joe Read More
Farm ManagementGenNext Growers Taking Marketing To The Next Level
July 7, 2015
In part two of our Marketing Tips From 14 GenNext Growers feature, we conclude with the remaining marketing and branding Read More
money
Insect & Disease Update$1 Million Citrus Greening Research Project Gets Green …
July 7, 2015
Funding approved in Florida's state budget to bolster development of beneficial bacteria-infused product. Read More
PotatoesNominations Open To Fill Board Seats For U.S. Potato Bo…
July 7, 2015
Fifty-four board members will be elected or re-elected to fill open seats on the United States Potato Board. Read More
More VegetablesGeorgia Court Tells Vidalia Onion Growers When They Can…
July 7, 2015
Concern was over the brand being hurt by shipping poor quality crops too soon in the season. Read More
Agritainment
CitrusAgritourism Gaining Lots Of Ground In Sunshine State
July 6, 2015
Researchers report more farming operations are growing revenue by hosting festivals, tours, wine tastings, and more. Read More
Photo of New Guinea flatworm found near Coral Gables, FL
CitrusSouth Florida’s Newest Pest Has Significant Ooze Factor
July 2, 2015
The infamous New Guinea flatworm, one of the ‘world's worst invasive alien species,’ might have found a new home. Read More
Farm ManagementPMA Advocates For Improvements To Proposed FSMA Mandato…
July 2, 2015
This week the Produce Marketing Association (PMA) submitted comments on behalf of its membership to FDA regarding the proposed Mandatory Read More
VegetablesUnited Fresh Leadership Program’s Class 20 Donates 28 S…
July 2, 2015
Over the past year, the twelve members of United Fresh Produce Industry Leadership Program’s Class 20 raised funds to support Read More
CitrusFlorida’s Young Farmers Working To Bridge Generation Ga…
July 2, 2015
Leadership conference to give GenNext Growers tools to become better agvocates. Read More
ProductionUse Broccoli Rotations To Reduce Disease And Minimize L…
July 1, 2015
Crop rotations are a key production practice utilized by every grower. You recognize the importance of rotations to break insect Read More
CitrusIndustry Stakeholders Rip Report Linking Citrus Consump…
July 1, 2015
Associations react swiftly; call out flaws in study released by the Journal of Clinical Oncology. Read More
Cucurbits11 Pumpkin And Squash Varieties
July 1, 2015
This month’s variety specs feature focuses on pumpkin and squash varieties. Features highlighted include great disease resistance packages, excellent yield potential, Read More
VegetablesInterview With Hazera Global Onion Product Manager
July 1, 2015
Onion is one of the most produced vegetable crops in the world. A lot of expertise is required to develop Read More
EquipmentHarvest Trends: More Mechanization Needed For Vegetable…
July 1, 2015
As the labor supply declines, industry experts and growers say investing in the latest harvesting technology will be necessary. Read More
healthy piece of citrus
Citrus Achievement AwardNeglected Research, Future Growers Top Of Mind For 2015…
July 1, 2015
Orie Lee advises young up-and-comers to supplement production knowledge with business acumen; calls for more focus on blight. Read More