Zone 9 planting calendar

Zone 9 is about winter cold, not spring frost

The USDA Plant Hardiness Zone Map divides the country by the average coldest winter night: each zone covers 10°F, and the "a" and "b" halves cover 5°F each. Zone 9 is the right guide for choosing perennials that survive the winter. It is only a rough guide to planting dates, because places with similar winter lows can have very different springs. That is why this page gives a range of frost dates rather than a single date, and why the frost date for your own location is a better input for the seed starting calculator.

Zone 9 is the clearest example of why a hardiness zone is not a frost date. It includes the Central Valley of California, the Gulf Coast, north Florida and the Pacific Northwest coast around Seattle and Portland. Median last frost dates among the example stations range from mid-January to mid-March, and the summers could hardly be more different. In the Gulf states and Florida, many vegetables are grown fall through spring; the UF/IFAS Florida Vegetable Gardening Guide, for example, lists August as well as spring planting windows for tomatoes in north Florida. In the Pacific Northwest, cool summers matter more than frost.

Typical frost dates in zone 9

The table lists example cities whose airport or city weather station falls in zone 9. "Last frost" is the date after which a 32°F freeze has a 50% chance of still happening; the "1-in-10" column is the date after which there is only a 10% chance. Planting tender crops after the 1-in-10 date is the cautious choice.