PlantAlong

When to plant peas in zone 6b

Transplant outdoors around Mar 25. That is 4 weeks before zone 6b's median last frost, Apr 221. Across most of zone 6b that date falls between Mar 13 and Apr 5.

Why a range: zone 6b is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Apr 10 to May 32, so a single zone date can be weeks off for you. The rule comes from Oregon State University Extension Service.

Last reviewed
Stations
899
ZIP codes
4,372
Photo: Mateusz Feliksik / Pexels
These dates use the typical last frost for the whole zone. Your ZIP code gives a closer answer.
  1. Start indoorsOregon State, central OR
  2. Transplant outdoorsOregon State, central OR
  3. Sow outdoorsColorado State
  • Start indoors
  • Plant outdoors
  • Range across the zone
  • Frost-free season (median)
  • Spring frost risk (90% to 10%)
  • Fall frost risk (10% to 90%)
Figure 1. Peas in zone 6b. Dark bars: at the zone's median frost dates. Pale bars: across most of the zone's ZIP codes. Hatched blue: where the zone's last and first frosts fall.
Start seeds indoors
Feb 268 weeks before last frost (Oregon State, central OR)
Transplant outdoors
Mar 25range Mar 13 – Apr 5

Five digits. The calendar is computed on your device.

What each source says, applied to zone 6b

The same frost dates give different answers depending on whose rule you follow. These are all the published rules we hold for peas, worked out at zone 6b's median frost dates.

Table 1. Peas rules from every source, at zone 6b's median last frost (Apr 22) and first frost (Oct 22).
SourceWhatRuleZone 6b median
Colorado State3Used aboveSow outdoors2-4 weeks before last frostMar 25 – Apr 8
Oregon State, central OR1Used aboveTransplant outdoors4 weeks before last frostMar 25
Oregon State, central OR1Used aboveStart indoors8 weeks before last frostFeb 26
Texas A&M (E-502)4Sow outdoors2-8 weeks before last frostFeb 26 – Apr 8
Texas A&M (E-502)4Plant for fall2-12 weeks before first frostJul 30 – Oct 8

Frost across zone 6b

  1. Last spring frostmedian Apr 22
  2. First fall frostmedian Oct 22
  • Frost-free season (median)
Figure 2. Frost dates across zone 6b, from 899 NOAA stations matched to 4,372 ZIP codes.

Sources

  1. Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
  2. NOAA National Centers for Environmental Information, U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), 2021. Retrieved 2026-11-02.
  3. Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
  4. Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.