PlantAlong

When to plant beans in zone 5a

Transplant outdoors around May 10. That is 1 weeks after zone 5a's median last frost, May 31. Across most of zone 5a that date falls between May 3 and May 27.

Why a range: zone 5a is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Apr 26 to May 202, so a single zone date can be weeks off for you. The rule comes from Oregon State University Extension Service.

Last reviewed
Stations
655
ZIP codes
2,089
Photo: Gobral / 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. Beans in zone 5a. 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
Apr 123 weeks before last frost (Oregon State, central OR)
Transplant outdoors
May 10range May 3 – May 27

Five digits. The calendar is computed on your device.

What each source says, applied to zone 5a

The same frost dates give different answers depending on whose rule you follow. These are all the published rules we hold for beans, worked out at zone 5a's median frost dates.

Table 1. Beans rules from every source, at zone 5a's median last frost (May 3) and first frost (Oct 5).
SourceWhatRuleZone 5a median
Colorado State3Used aboveSow outdoorsOn the last frostMay 3
Utah State4Sow outdoorsOn the last frostMay 3
Oregon State, central OR1Used aboveTransplant outdoors1 weeks after last frostMay 10
Oregon State, central OR1Used aboveStart indoors3 weeks before last frostApr 12
Texas A&M (E-502)5Sow outdoors1-4 weeks after last frostMay 10 – May 31
Texas A&M (E-502)5Plant for fall8-10 weeks before first frostJul 27 – Aug 10
Texas A&M (E-502)5Plant for fall14-16 weeks before first frostJun 15 – Jun 29

Frost across zone 5a

  1. Last spring frostmedian May 3
  2. First fall frostmedian Oct 5
  • Frost-free season (median)
Figure 2. Frost dates across zone 5a, from 655 NOAA stations matched to 2,089 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. Utah State University Extension, Suggested Vegetable Planting Dates for Utah, January 2018; revised May 2025. Retrieved 2026-11-02.
  5. Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.