PlantAlong

When to plant peas in zone 8b

Transplant outdoors around Feb 18. That is 4 weeks before zone 8b's median last frost, Mar 171. Across most of zone 8b that date falls between Feb 7 and Mar 4.

Why a range: zone 8b is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Mar 6 to Apr 12, so a single zone date can be weeks off for you. The rule comes from Oregon State University Extension Service.

Last reviewed
Stations
652
ZIP codes
2,535
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 8b. 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
Jan 218 weeks before last frost (Oregon State, central OR)
Transplant outdoors
Feb 18range Feb 7 – Mar 4

Five digits. The calendar is computed on your device.

What each source says, applied to zone 8b

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 8b's median frost dates.

Table 1. Peas rules from every source, at zone 8b's median last frost (Mar 17) and first frost (Nov 13).
SourceWhatRuleZone 8b median
Colorado State3Used aboveSow outdoors2-4 weeks before last frostFeb 18 – Mar 3
Oregon State, central OR1Used aboveTransplant outdoors4 weeks before last frostFeb 18
Oregon State, central OR1Used aboveStart indoors8 weeks before last frostJan 21
Texas A&M (E-502)4Sow outdoors2-8 weeks before last frostJan 21 – Mar 3
Texas A&M (E-502)4Plant for fall2-12 weeks before first frostAug 21 – Oct 30

Frost across zone 8b

  1. Last spring frostmedian Mar 17
  2. First fall frostmedian Nov 13
  • Frost-free season (median)
Figure 2. Frost dates across zone 8b, from 652 NOAA stations matched to 2,535 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.