Chicago is primarily in USDA Plant Hardiness Zone 6a, with some areas, especially near the lakefront, classified as Zone 6b. Zone 6a corresponds to average minimum winter temperatures between -10°F and -5°F, while Zone 6b ranges from -5°F to 0°F
. This shift from the previous Zone 5 classification reflects a warming trend and allows for a broader range of plants to be grown, including some that were traditionally more common in warmer southern regions. However, local microclimates within the city, influenced by urban features like buildings and concrete, can create variations where some spots might even approach Zone 7 conditions
. In summary, Chicago's plant hardiness zone is mostly Zone 6a, with parts in 6b, indicating a moderate cold tolerance for plants suitable for the area.
