What the USDA’s new plant hardiness map means for your garden

At last. Finally, there’s an updated official government resource out there that gardeners all across the land can blame for any failed planting efforts.

OK, maybe not for all failed plantings, but at least there’s one more arrow in the gardener’s quiver to help us all be a bit more successful in our efforts.

After many years of analyzing gigantic reams of meteorological data, consulting the weather rock on the front lawn of the USDA building in Beltsville, Maryland and dusting off the official government-issued Ouija board, our friends at the United States Department of Agriculture have issued a long-awaited update to the cold hardiness zone map.

If you’re not familiar with the map, it is a graphic representation of the United States broken into 26 zones based on average annual minimum temperature. For decades, this map has been used by gardeners to determine what plants might have a chance and which selections don’t have a prayer in any particular patch of US dirt. It’s become an industry standard that makes gardening feel a bit less like you’re staring down the barrel of Dirty Harry’s 44 magnum ― “Do you feel lucky, Punk?”

What is the USDA cold hardiness zone map?

Snow covers flowers near the Dubuque Arboretum and Botanical Garden Saturday, April 27, 2019 in Dubuque, Iowa.

A little history. Since the dawn of time, gardeners have asked a simple question, “will that grow here?” And for just as long, the most common answer was probably, “I dunno. Give it a try . . .” Then, back in the 1920s, an enterprising group at Harvard University’s Arnold Arboretum decided to create a map that would at least help out on the winter survival part of that age-old question. They mapped out zones across the US to give gardeners some idea of how cold it generally gets during a typical winter. And over time gardeners

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