PlantAlong
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Zone 6b

The coldest winter night here averages -5 to 0°F1. Frost dates vary more than that suggests.

ZIP codes
5,271
Weather stations
899
Last reviewed
Your zone tells you how cold winter gets. It does not tell you when to plant.
Typical last frost
Apr 22most ZIPs Apr 10 – May 3
Typical first frost
Oct 22most ZIPs Oct 10 – Oct 29
Spread in spring
23 daysbetween early and late ZIPs
  1. Last spring frostmedian Apr 22
  2. First fall frostmedian Oct 22
  • Frost-free season (median)
Figure 1. When frosts fall across zone 6b: the full range (pale), most ZIP codes (10th to 90th percentile, solid) and the median (marker). From 899 NOAA stations matched to 4,372 ZIP codes.

Zone and frost date are different things. The zone comes from the coldest winter night; frost dates come from spring and fall temperatures at weather stations2. Your own dates can sit anywhere in the range above, so the calendar for your ZIP is the better guide.

Five digits. The calendar is computed on your device.

When to plant in zone 6b

Each crop uses its primary extension source, applied to this zone's frost spread. Rules written for another state are labelled with their source.

  1. Tomatoes
  2. Peppers
  3. Cucumbers
  4. Zucchini
  5. Beans
  6. Peas
  7. Lettuce
  8. Carrots
  9. Onions
  10. Garlic
  11. Potatoes
  12. BasilNo sourced window
  • 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 2. Planting windows across zone 6b. Solid and dashed bars: the window at the zone's median frost dates. Pale bars: where the same window falls across most of the zone's ZIP codes.
Table 1. Planting windows in zone 6b.
CropWhatZone medianAcross most of the zoneSource
TomatoesStart indoorsFeb 26Feb 14 – Mar 8Oregon State, central OR3
Transplant outdoorsMay 6Apr 24 – May 17Colorado State4
PeppersStart indoorsMar 11Feb 28 – Mar 22Oregon State, central OR3
Transplant outdoorsMay 6Apr 24 – May 17Colorado State4
CucumbersStart indoorsApr 8Mar 27 – Apr 19Oregon State, central OR3
Transplant outdoorsApr 29Apr 17 – May 10Oregon State, central OR3
Sow outdoorsApr 22Apr 10 – May 3Colorado State4
ZucchiniStart indoorsApr 15Apr 3 – Apr 26Oregon State, central OR3
Transplant outdoorsMay 6Apr 24 – May 17Oregon State, central OR3
Sow outdoorsApr 22Apr 10 – May 3Colorado State4
BeansStart indoorsApr 1Mar 20 – Apr 12Oregon State, central OR3
Transplant outdoorsApr 29Apr 17 – May 10Oregon State, central OR3
Sow outdoorsApr 22Apr 10 – May 3Colorado State4
PeasStart indoorsFeb 26Feb 14 – Mar 8Oregon State, central OR3
Transplant outdoorsMar 25Mar 13 – Apr 5Oregon State, central OR3
Sow outdoorsMar 25 – Apr 8Mar 13 – Apr 19Colorado State4
LettuceStart indoorsMar 4Feb 21 – Mar 15Oregon State, central OR3
Transplant outdoorsApr 8Mar 27 – Apr 19Oregon State, central OR3
Sow outdoorsMar 25 – Apr 8Mar 13 – Apr 19Colorado State4
CarrotsSow outdoorsApr 8 – Apr 22Mar 27 – May 3Colorado State4
OnionsStart indoorsJan 1Dec 20 – Jan 12Oregon State, central OR3
Transplant outdoorsMar 11Feb 28 – Mar 22Oregon State, central OR3
Sow outdoorsMar 25 – Apr 8Mar 13 – Apr 19Colorado State4
GarlicPlant for fallOct 29 – Nov 5Oct 17 – Nov 12Wisconsin5
PotatoesSow outdoorsApr 8 – Apr 22Mar 27 – May 3Colorado State4
BasilNo frost-relative rule is published; sources give conditions instead (see the crop page).

Sources

  1. PRISM Group, Oregon State University, 2023 USDA Plant Hardiness Zone Map ZIP code data (PHZM 2023), 2023-11-15. 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. Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
  4. Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
  5. University of Wisconsin–Madison Division of Extension, Wisconsin Horticulture, Garlic, Allium sativum, Rev: 10/2023. Retrieved 2026-11-02.