Garden zones became a “hot topic” this month when the U.S. Department of Agriculture unveiled the new Plant Hardiness Zone Map.
The Plant Hardiness Zone Map is a breakdown of annual minimum temperature averages that occur in a region over several decades. The maps are periodically updated by the USDA, but until last week the latest update happened in 1990. The new version of the map not only takes into consideration temperatures, but also elevation, proximity to water, slope and wind.
West Virginia University Kanawha County Extension Agent John Porter said that while the changes for the state on average were small, there is a noticeable shift for some regions.
“We’re seeing a slight shifting to the north as far as temperatures are concerned,” Porter, the county’s agriculture and natural resources agent, said. “These shifts are nationwide and do affect areas of the state that were near the old zone map borders.”
In fact, West Virginia now has a few spots in the state that are classified as a “Zone 7a.” This means that gardeners can plant new types of flowers or vegetables in those areas. These spots are most prevalent across southern West Virginia counties.
This doesn’t come as a surprise to Porter, who has been growing a Cameilla sinensis – the plant used to make black and green teas in China – in his Kanawha County backyard for the past two years. The plant is normally a Zone 7 plant, but his property falls within a narrow band of zone 7a, along the Kanawha River.
“This doesn’t mean people should go out and spend a lot of money on Zone 7a plants,” he cautions. Instead, Porter recommends ordering one or two new plants and monitoring the success rate of those.
“Many of the plants for the new zones likely won’t yet be carried by your local greenhouses,” he said. He suggests ordering the plants online or from mail-order catalogs until more become available locally.
One of the most unique features of the new map is the ability to visit the USDA website, type in a specific zip code and see the exact zone hardiness for that area. Porter recommends doing this before planning or making new purchases for your garden. It is also a good idea for everyone to take a look at the map to see if they are still in the same zone.
“Our gardeners can now be more targeted and specific when it comes to planting for their region,” Porter said.
He also notes that these changes aren’t exactly “news” to gardeners who have been using resources like the WVU Extension Service Garden Calendar when planning their growing seasons.
“We’ve been following the trends for years now and the average ‘last frost date’ for areas of the state has been earlier in the last few years,” Porter said. “The WVU Extension Garden Calendar has reflected that change in recent years. Earlier frost-free dates mean for longer growing periods. This new guide line just helps us be even more targeted for specific planting zones.”
For more information on the new USDA Plant Hardiness Zone Maps, visit www.planthardiness.ars.usda.gov, or contact your local county office of the WVU Extension Service.
CONTACT: Cassie Waugh, WVU Extension Service
Office: 304-293-8735; Cell: 304-376-1829