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The One Minute Geographer: Shifting Planting Zones
Today the One Minute Geographer is looking at the impact of climate change on crop planting and gardening. We’ve all seen those planting zone maps that tell us what kinds of flowers, shrubs or vegetables we can plant in our regions.
NOAA and the folks at Climate.gov have given us a handy measure of how planting zones are getting warmer and, in effect, shifting northward, between 1971 and 2010. Everything you see on the map above indicates warming; that is the expansion of more southerly zones farther north.
The swirly pattern in much of the West reflects its mountains and the movement of zones uphill to higher elevations. In mountainous areas where temperatures fall on average 3.3 degree per thousand feet, elevation can be a more important determinant of climate than latitude. That’s why we can have snow capped Andes Mountains on the Equator!
The primary factor measured in these maps is the warming up of the average overnight low temperatures — those frosts that can kill seedlings and young plants. Those first and last frosts of each year roughly determine the “growing season” (zone) of your location.
