USDA Plant Hardiness Zone
Zone 5b Frost Dates & Planting Calendar
2,458 ZIP codes across 28 states fall in zone 5b.
- Zone
- 5b
- Average Annual Low
- -15 to -10°F
- Typical Growing Season
- 153 days
- ZIP Codes
- 2,458
What zone 5b actually tells you
A hardiness zone describes one thing: the average coldest night of the year, which in zone 5b falls between -15 to -10°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 5b spans 28 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.