Seattle is currently classified in USDA Plant Hardiness Zones 9a and 9b. Zone 9a corresponds to average minimum winter temperatures of 20°F to 25°F, and Zone 9b corresponds to 25°F to 30°F. This update was part of the USDA's 2023 revision of the Hardiness Zone Map, which shifted Seattle from its previous zone 8b to 9a, reflecting a warming trend in the region's climate
. This change means Seattle gardeners can potentially grow a wider range of plants that are hardy to Zone 9a conditions, similar to those found in northern Florida. However, the zones only reflect average minimum winter temperatures and do not account for other factors like soil, moisture, heat, or erratic weather patterns, so gardeners should still consider local microclimates and other environmental conditions when selecting plants
