PlantAlong

When to plant peppers in zone 6a

Transplant outdoors around May 12. That is 2 weeks after zone 6a's median last frost, Apr 281. Across most of zone 6a that date falls between Apr 30 and May 24.

Why a range: zone 6a is defined by winter lows, not frost dates. Its ZIP codes have median last frosts from Apr 16 to May 102, so a single zone date can be weeks off for you. The rule comes from Colorado State University Extension, written for CO and applied here to zone 6a's frost dates.

Last reviewed
Stations
924
ZIP codes
4,375
Photo: Yan Krukau / 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 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. Peppers in zone 6a. 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
Mar 176 weeks before last frost (Oregon State, central OR)
Transplant outdoors
May 12range Apr 30 – May 24
First harvest, roughly
Jul 2170 days from transplant1

Five digits. The calendar is computed on your device.

What each source says, applied to zone 6a

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

Table 1. Peppers rules from every source, at zone 6a's median last frost (Apr 28) and first frost (Oct 17).
SourceWhatRuleZone 6a median
Colorado State1Used aboveTransplant outdoors2 weeks after last frostMay 12
Utah State3Transplant outdoors2 weeks after last frostMay 12
Oregon State, central OR4Transplant outdoors2 weeks after last frostMay 12
Oregon State, central OR4Used aboveStart indoors6 weeks before last frostMar 17
Texas A&M (E-502)5Transplant outdoors1-8 weeks after last frostMay 5 – Jun 23
Texas A&M (E-502)5Plant for fall12-16 weeks before first frostJun 27 – Jul 25

Frost across zone 6a

  1. Last spring frostmedian Apr 28
  2. First fall frostmedian Oct 17
  • Frost-free season (median)
Figure 2. Frost dates across zone 6a, from 924 NOAA stations matched to 4,375 ZIP codes.

Sources

  1. Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 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. Utah State University Extension, Suggested Vegetable Planting Dates for Utah, January 2018; revised May 2025. Retrieved 2026-11-02.
  4. Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. 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.