Agr. Zone Map
UPDATED VERSION OF THE PLANT HARDINESS ZONE MAP
Consult the Plant Hardiness Zone Map to find out what peony variety will thrive in your area. Peonies require winter cold to flourish. However, some areas have those pocket areas that will allow your peonies to grow well. The Hardiness Zones were developed to support you in making informted decisions.
The USDA has released an updated version of the Plant Hardiness Zone Map, with adjusted zones and more helpful online features. This is the first update since the map was created in 1990. The USDA’s Agricultural Research Service teamed with Oregon State University’s PRISM Climate Group to develop the new map. The team created drafts of the map and then consulted with climatic experts across the country to make revisions for the final map.
Changes since 1990
The new map shows shifts in the boundaries of the zones drawn in 1990. The majority of locations are now a half-zone warmer (5 degrees) than indicated on the 1990 map. Some locations are now in cooler zones. The new map shows shifts in the boundaries of the zones drawn in 1990. The majority of locations are now a half-zone warmer (5 degrees) than indicated on the 1990 map. Some locations are now in cooler zones. The new map shows shifts in the boundaries of the zones drawn in 1990. The majority of locations are now a half-zone warmer (5 degrees) than indicated on the 1990 map. Some locations are now in cooler zones.
The USDA and OSU attribute the changes to these facts:
- They used data measured at weather stations over a 30 year period (1976–2005), while the 1990 map used data from a 13-year period (1974–1986).
- They used new measurement methods, including algorithms that considered changes in elevation, proximity to large bodies of water and extremes of terrain (peaks and valleys), which all affect temperature.
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