What USDA hardiness zones do — and don't — tell you
The USDA Plant Hardiness Zone Map (most recently updated in 2023) divides North America into zones based on the average annual extreme minimum winter temperature, in 10°F bands split into 'a' and 'b' halves. The 2023 update shifted many areas about half a zone warmer than the 2012 map.
What the zone tells you is narrow but important: whether a perennial, shrub, or tree can survive your average coldest winter night. That is it.
