USDA Plant Hardiness Zone
Zone 9a Frost Dates & Planting Calendar
1,662 ZIP codes across 16 states fall in zone 9a.
- Zone
- 9a
- Average Annual Low
- 20 to 25°F
- Typical Growing Season
- 262 days
- ZIP Codes
- 1,662
What zone 9a actually tells you
A hardiness zone describes one thing: the average coldest night of the year, which in zone 9a falls between 20 to 25°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 9a spans 16 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.