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USDA updates plant hardiness zones map

Seed packets won't likely reflect the change until 2013

January 31, 2012|Meteorologist Brent Watts
  • The USDA has updated plant hardiness zones for the United States based on new climate data from 1990 to 2005.
The USDA has updated plant hardiness zones for the United States based on new climate data from 1990 to 2005.

On the back of seed packets you'll find a map of "hardiness zones," or zones where plants are best suited to grow.

The zone map is created by the United States Department of Agriculture and  has been used for decades by amateur and professional gardeners as a guide to yearly planting.

So why all the changes?

The USDA has found through research from the past few decades, that a general warming trend has taken place across the U.S. from 1990 to 2005.

This means the new map should be more precise than the previous map published in 1990.

Each zone on the map is based on 10 degrees Fahrenheit variations in the coldest average temperature expected in the region. Zone 2 is the coldest region for the U.S., where the average minimum temperature is -40 to -50.

The Arbor Day foundations, suggests "the new 2006 Hardiness Zone Map is consistent with the consensus of climate scientists that global warming is underway."

What does this mean for southwest Virginia?

The new map offers very few changes across southwest Virginia. The main difference is in Zone 7, which now expands westward into the New River Valley. Zone 6, our mainly mountain zones, saw the fewest changes with the new map.

Bruce Feldberg with Riverside Nursery in Salem, says "most farmers and gardeners are already aware of the changing conditions over the past decade." This new USDA map only makes it official.

In some regions of the country the change means farmers and gardeners there can select plants and seed varieties that are less tolerant of cold weather than what they have planted in the past.

Will my seed packets show the new map?

Probably not. Most of the seed packets have been printed for this year. So, the new maps will be added to next year's seed packs.

Where can I find which zone I'm in?


CHANGES FROM 1990 to 2006


The advantage of the new map is gardeners and farmers can type in their ZIP code at the USDA website and learn the specific hardiness zone for their community.

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