Zone 8b

The coldest winter night here averages 15 to 20°F1. Frost dates vary more than that suggests.

ZIP codes: 3,379
Weather stations: 652
Last reviewed: 2026-11-02

Your zone tells you how cold winter gets. It does not tell you when to plant.

Typical last frost: Mar 17most ZIPs Mar 6 – Apr 1
Typical first frost: Nov 13most ZIPs Nov 4 – Nov 23
Spread in spring: 26 daysbetween early and late ZIPs

Last spring frostmedian Mar 17Full range across the zone: Feb 11 to Jun 3Most of the zone (10th to 90th percentile): Mar 6 to Apr 1Zone median: Mar 17
First fall frostmedian Nov 13Full range across the zone: Sep 14 to Dec 13Most of the zone (10th to 90th percentile): Nov 4 to Nov 23Zone median: Nov 13

Frost-free season (median)

Figure 1. When frosts fall across zone 8b: the full range (pale), most ZIP codes (10th to 90th percentile, solid) and the median (marker). From 652 NOAA stations matched to 2,535 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.

When to plant in zone 8b

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

TomatoesStart indoors across most of the zone: Jan 10 to Feb 5Start indoors at the zone median: Jan 21 (Oregon State, central OR)Transplant outdoors across most of the zone: Mar 20 to Apr 15Transplant outdoors at the zone median: Mar 31 (Colorado State)
PeppersStart indoors across most of the zone: Jan 24 to Feb 19Start indoors at the zone median: Feb 4 (Oregon State, central OR)Transplant outdoors across most of the zone: Mar 20 to Apr 15Transplant outdoors at the zone median: Mar 31 (Colorado State)
CucumbersStart indoors across most of the zone: Feb 21 to Mar 18Start indoors at the zone median: Mar 3 (Oregon State, central OR)Transplant outdoors across most of the zone: Mar 13 to Apr 8Transplant outdoors at the zone median: Mar 24 (Oregon State, central OR)Sow outdoors across most of the zone: Mar 6 to Apr 1Sow outdoors at the zone median: Mar 17 (Colorado State)
ZucchiniStart indoors across most of the zone: Feb 28 to Mar 25Start indoors at the zone median: Mar 10 (Oregon State, central OR)Transplant outdoors across most of the zone: Mar 20 to Apr 15Transplant outdoors at the zone median: Mar 31 (Oregon State, central OR)Sow outdoors across most of the zone: Mar 6 to Apr 1Sow outdoors at the zone median: Mar 17 (Colorado State)
BeansStart indoors across most of the zone: Feb 14 to Mar 11Start indoors at the zone median: Feb 25 (Oregon State, central OR)Transplant outdoors across most of the zone: Mar 13 to Apr 8Transplant outdoors at the zone median: Mar 24 (Oregon State, central OR)Sow outdoors across most of the zone: Mar 6 to Apr 1Sow outdoors at the zone median: Mar 17 (Colorado State)
PeasStart indoors across most of the zone: Jan 10 to Feb 5Start indoors at the zone median: Jan 21 (Oregon State, central OR)Transplant outdoors across most of the zone: Feb 7 to Mar 4Transplant outdoors at the zone median: Feb 18 (Oregon State, central OR)Sow outdoors across most of the zone: Feb 7 to Mar 18Sow outdoors at the zone median: Feb 18 to Mar 3 (Colorado State)
LettuceStart indoors across most of the zone: Jan 17 to Feb 12Start indoors at the zone median: Jan 28 (Oregon State, central OR)Transplant outdoors across most of the zone: Feb 21 to Mar 18Transplant outdoors at the zone median: Mar 3 (Oregon State, central OR)Sow outdoors across most of the zone: Feb 7 to Mar 18Sow outdoors at the zone median: Feb 18 to Mar 3 (Colorado State)
CarrotsSow outdoors across most of the zone: Feb 21 to Apr 1Sow outdoors at the zone median: Mar 3 to Mar 17 (Colorado State)
OnionsStart indoors across most of the zone: Nov 15 to Dec 11Start indoors at the zone median: Nov 26 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 24 to Feb 19Transplant outdoors at the zone median: Feb 4 (Oregon State, central OR)Sow outdoors across most of the zone: Feb 7 to Mar 18Sow outdoors at the zone median: Feb 18 to Mar 3 (Colorado State)
GarlicPlant for fall across most of the zone: Nov 11 to Dec 7Plant for fall at the zone median: Nov 20 to Nov 27 (Wisconsin)
PotatoesSow outdoors across most of the zone: Feb 21 to Apr 1Sow outdoors at the zone median: Mar 3 to Mar 17 (Colorado State)
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 8b. 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 8b.
Crop	What	Zone median	Across most of the zone	Source
Tomatoes	Start indoors	Jan 21	Jan 10 – Feb 5	Oregon State, central OR3
Tomatoes	Transplant outdoors	Mar 31	Mar 20 – Apr 15	Colorado State4
Peppers	Start indoors	Feb 4	Jan 24 – Feb 19	Oregon State, central OR3
Peppers	Transplant outdoors	Mar 31	Mar 20 – Apr 15	Colorado State4
Cucumbers	Start indoors	Mar 3	Feb 21 – Mar 18	Oregon State, central OR3
	Transplant outdoors	Mar 24	Mar 13 – Apr 8	Oregon State, central OR3
	Sow outdoors	Mar 17	Mar 6 – Apr 1	Colorado State4
Zucchini	Start indoors	Mar 10	Feb 28 – Mar 25	Oregon State, central OR3
	Transplant outdoors	Mar 31	Mar 20 – Apr 15	Oregon State, central OR3
	Sow outdoors	Mar 17	Mar 6 – Apr 1	Colorado State4
Beans	Start indoors	Feb 25	Feb 14 – Mar 11	Oregon State, central OR3
	Transplant outdoors	Mar 24	Mar 13 – Apr 8	Oregon State, central OR3
	Sow outdoors	Mar 17	Mar 6 – Apr 1	Colorado State4
Peas	Start indoors	Jan 21	Jan 10 – Feb 5	Oregon State, central OR3
	Transplant outdoors	Feb 18	Feb 7 – Mar 4	Oregon State, central OR3
	Sow outdoors	Feb 18 – Mar 3	Feb 7 – Mar 18	Colorado State4
Lettuce	Start indoors	Jan 28	Jan 17 – Feb 12	Oregon State, central OR3
	Transplant outdoors	Mar 3	Feb 21 – Mar 18	Oregon State, central OR3
	Sow outdoors	Feb 18 – Mar 3	Feb 7 – Mar 18	Colorado State4
Carrots	Sow outdoors	Mar 3 – Mar 17	Feb 21 – Apr 1	Colorado State4
Onions	Start indoors	Nov 26	Nov 15 – Dec 11	Oregon State, central OR3
	Transplant outdoors	Feb 4	Jan 24 – Feb 19	Oregon State, central OR3
	Sow outdoors	Feb 18 – Mar 3	Feb 7 – Mar 18	Colorado State4
Garlic	Plant for fall	Nov 20 – Nov 27	Nov 11 – Dec 7	Wisconsin5
Potatoes	Sow outdoors	Mar 3 – Mar 17	Feb 21 – Apr 1	Colorado State4
Basil	No frost-relative rule is published; sources give conditions instead (see the crop page).

Sources

PRISM Group, Oregon State University, 2023 USDA Plant Hardiness Zone Map ZIP code data (PHZM 2023), 2023-11-15. Retrieved 2026-11-02.
NOAA National Centers for Environmental Information, U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), 2021. Retrieved 2026-11-02.
Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
University of Wisconsin–Madison Division of Extension, Wisconsin Horticulture, Garlic, Allium sativum, Rev: 10/2023. Retrieved 2026-11-02.