USDA Plant Hardiness Zone
Zone 9b Frost Dates & Planting Calendar
1,405 ZIP codes across 10 states fall in zone 9b.
- Zone
- 9b
- Average Annual Low
- 25 to 30°F
- Typical Growing Season
- 304 days
- ZIP Codes
- 1,405
What zone 9b actually tells you
A hardiness zone describes one thing: the average coldest night of the year, which in zone 9b falls between 25 to 30°F. It answers whether a perennial will survive the winter — not when to plant in spring.
Frost dates answer the planting question, and they vary widely inside a single zone. Zone 9b spans 10 states, and a coastal ZIP can differ from an inland one by three weeks despite sharing the zone. Pick your own ZIP code below rather than planting by zone alone.