The National Arbor Day Foundation has updated the plant hardiness zone map. Find out what impact the planting zone changes will have.
The National Arbor Day Foundation has released new plant hardiness zone maps, based upon data from 5,000 National Climatic Data centers across the continental United States. The foundation also released a map that shows the changes that have taken place in hardiness zones throughout the U.S. since 1990, the year of the last map update.
What Are Plant Hardiness Zones?
The plant hardiness zones are a guide that gardeners can use to determine which plants will grow best in a particular climate. The zones divide the U.S. and Canada into eleven areas depending on average minimum temperature. There is a 10 degree Fahrenheit difference between zones. For example, zone 4 could get as cold as -30 degrees Fahrenheit in the winter, while zone 5 could get as cold as -20 degrees.
How Have the Planting Zones Changed?
Many areas of the U.S. have gone up a zone. In 1990, most of upstate NY was a zone 5, northern NY was a zone 4, and the higher elevations of the Adirondacks were a zone 3. On the updated map, much of the upstate region is a zone 6, while only a small area remains a zone 5. Northern NY remains a zone 4, but much of the Adirondack region is now also a zone 4.
What Are the Benefits of the Changes in the Planting Zones?
Some garden centers in Upstate NY are now stocking plants that will survive in zone 6. Because of this, gardeners will find a wider selection when shopping for plants this year. A side benefit is that the growing season will be longer throughout much of the U.S.
What Are Some Potential Problems of the Changes in the Planting Zones?
While this will introduce some interesting new plants to many areas, some plants that need the colder temperatures of winter are suffering. New York’s official state tree is the sugar maple, which needs cold temperatures to thrive. Maples have, sadly, begun a gradual decline. Scientists are predicting that untended maples, which dot the upstate NY landscape, will disappear in 100 years. Oak and hickory trees, which grow faster than maples, will crowd out maple seedlings in the forest. Eventually, maple trees will be a rare sight in many northern regions of the U.S.
Contact The National Arbor Day Foundation for more information.
Sources:
Albany Times Union, Judging by the Azaleas, Winter is Losing its Bite, Brian Nearing, May 8, 2007
