The USDA's gardening zones have shifted. (Interactive app and map)

7 hours ago

The USDA updated its plant hardiness zone map for the first time in 11 years, reflecting changes in climate and data quality.
The new map shows an average increase of 3.3°F in the lowest winter temperatures compared to the previous period, with most changes due to warming winters.
Hardiness zones indicate the average coldest temperature over 30 years and help predict winter survival for perennials like trees and shrubs.
However, zones have limitations: they don't account for extreme low temperatures, frequency of cold snaps, or summer heat extremes.
Different regions with the same zone (e.g., Juneau, Boston, Santa Fe) have varying climates, so zones alone can't dictate plant suitability.
Gardeners should use the map as one tool among many, consulting local experts, nurseries, or cooperative extension services for tailored advice.
With warmer zones, some plants like camellias and figs are becoming hardier in areas like Philadelphia, but microclimates in gardens also affect plant survival.

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