The 2012 USDA planting zone map

Climate change skeptics be damned, the new Dept. of Agriculture plant hardiness map shows a distinct northward warming trend.

These are the brightly colored maps on seed packets familiar to gardeners all over the country, showing what plants can survive where. This is the first updated map since 1990, and is based on a broader set of weather and temperature data than earlier maps.

Where there were 10 zones before, now there are 12 – one hotter (Hawaii) and one colder (Alaska) have been added. Each zone represents a 10-degree range for the coldest average temperature, and comparing the older with the newer, it is clear there is a warming trend northward.

To help account for local variations, the USDA website now enables gardeners to enter their zip code and find the lowest average temperature for an area within a half-mile of their gardens.

They can be found at: