Hardiness zone

Zone 10a

The coldest winter night here averages 30 to 35°F1. Frost dates vary more than that suggests.

ZIP codes: 1,234
Weather stations: 171
Last reviewed: 2026-11-02

Photo: Alexander Aubin / Pexels

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

Typical last frost: Jan 17most ZIPs Jan 2 – Jan 30
Typical first frost: Jan 3most ZIPs Dec 19 – Jan 13
Spread in spring: 28 daysbetween early and late ZIPs

Last spring frostmedian Jan 17Full range across the zone: Dec 29 to Apr 11Most of the zone (10th to 90th percentile): Jan 2 to Jan 30Zone median: Jan 17
First fall frostmedian Jan 3Full range across the zone: Nov 8 to Feb 1Most of the zone (10th to 90th percentile): Dec 19 to Jan 13Zone median: Jan 3

Frost-free season (median)

Figure 1. When frosts fall across zone 10a: the full range (pale), most ZIP codes (10th to 90th percentile, solid) and the median (marker). From 171 NOAA stations matched to 707 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 10a

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: Nov 7 to Dec 5Start indoors at the zone median: Nov 22 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 16 to Feb 13Transplant outdoors at the zone median: Jan 31 (Colorado State)Plant for fall across most of the zone: Sep 12 to Oct 21Plant for fall at the zone median: Sep 27 to Oct 11 (Texas A&M (E-502))
PeppersStart indoors across most of the zone: Nov 21 to Dec 19Start indoors at the zone median: Dec 6 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 16 to Feb 13Transplant outdoors at the zone median: Jan 31 (Colorado State)Plant for fall across most of the zone: Aug 29 to Oct 21Plant for fall at the zone median: Sep 13 to Oct 11 (Texas A&M (E-502))
CucumbersStart indoors across most of the zone: Dec 19 to Jan 16Start indoors at the zone median: Jan 3 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 9 to Feb 6Transplant outdoors at the zone median: Jan 24 (Oregon State, central OR)Sow outdoors across most of the zone: Jan 2 to Jan 30Sow outdoors at the zone median: Jan 17 (Colorado State)Plant for fall across most of the zone: Sep 26 to Nov 4Plant for fall at the zone median: Oct 11 to Oct 25 (Texas A&M (E-502))
ZucchiniStart indoors across most of the zone: Dec 26 to Jan 23Start indoors at the zone median: Jan 10 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 16 to Feb 13Transplant outdoors at the zone median: Jan 31 (Oregon State, central OR)Sow outdoors across most of the zone: Jan 2 to Jan 30Sow outdoors at the zone median: Jan 17 (Colorado State)Plant for fall across most of the zone: Sep 5 to Oct 21Plant for fall at the zone median: Sep 20 to Oct 11 (Texas A&M (E-502))
BeansStart indoors across most of the zone: Dec 12 to Jan 9Start indoors at the zone median: Dec 27 (Oregon State, central OR)Transplant outdoors across most of the zone: Jan 9 to Feb 6Transplant outdoors at the zone median: Jan 24 (Oregon State, central OR)Sow outdoors across most of the zone: Jan 2 to Jan 30Sow outdoors at the zone median: Jan 17 (Colorado State)Plant for fall across most of the zone: Oct 10 to Nov 18Plant for fall at the zone median: Oct 25 to Nov 8 (Texas A&M (E-502))Plant for fall across most of the zone: Aug 29 to Oct 7Plant for fall at the zone median: Sep 13 to Sep 27 (Texas A&M (E-502))
PeasStart indoors across most of the zone: Nov 7 to Dec 5Start indoors at the zone median: Nov 22 (Oregon State, central OR)Transplant outdoors across most of the zone: Dec 5 to Jan 2Transplant outdoors at the zone median: Dec 20 (Oregon State, central OR)Sow outdoors across most of the zone: Dec 5 to Jan 16Sow outdoors at the zone median: Dec 20 to Jan 3 (Colorado State)Plant for fall across most of the zone: Sep 26 to Dec 30Plant for fall at the zone median: Oct 11 to Dec 20 (Texas A&M (E-502))
LettuceStart indoors across most of the zone: Nov 14 to Dec 12Start indoors at the zone median: Nov 29 (Oregon State, central OR)Transplant outdoors across most of the zone: Dec 19 to Jan 16Transplant outdoors at the zone median: Jan 3 (Oregon State, central OR)Sow outdoors across most of the zone: Dec 5 to Jan 16Sow outdoors at the zone median: Dec 20 to Jan 3 (Colorado State)Plant for fall across most of the zone: Sep 12 to Nov 4Plant for fall at the zone median: Sep 27 to Oct 25 (Texas A&M (E-502))
CarrotsSow outdoors across most of the zone: Dec 19 to Jan 30Sow outdoors at the zone median: Jan 3 to Jan 17 (Colorado State)Plant for fall across most of the zone: Sep 12 to Oct 21Plant for fall at the zone median: Sep 27 to Oct 11 (Texas A&M (E-502))
OnionsStart indoors across most of the zone: Sep 12 to Oct 10Start indoors at the zone median: Sep 27 (Oregon State, central OR)Transplant outdoors across most of the zone: Nov 21 to Dec 19Transplant outdoors at the zone median: Dec 6 (Oregon State, central OR)Sow outdoors across most of the zone: Dec 5 to Jan 16Sow outdoors at the zone median: Dec 20 to Jan 3 (Colorado State)Plant for fall across most of the zone: Oct 10 to Nov 18Plant for fall at the zone median: Oct 25 to Nov 8 (Texas A&M (E-502))
GarlicPlant for fall across most of the zone: Dec 26 to Jan 27Plant for fall at the zone median: Jan 10 to Jan 17 (Wisconsin)
PotatoesSow outdoors across most of the zone: Dec 19 to Jan 30Sow outdoors at the zone median: Jan 3 to Jan 17 (Colorado State)Plant for fall across most of the zone: Aug 29 to Oct 7Plant for fall at the zone median: Sep 13 to Sep 27 (Texas A&M (E-502))
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 10a. 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 10a.
Crop	What	Zone median	Across most of the zone	Source
Tomatoes	Start indoors	Nov 22	Nov 7 – Dec 5	Oregon State, central OR3
	Transplant outdoors	Jan 31	Jan 16 – Feb 13	Colorado State4
	Plant for fall	Sep 27 – Oct 11	Sep 12 – Oct 21	Texas A&M (E-502)5
Peppers	Start indoors	Dec 6	Nov 21 – Dec 19	Oregon State, central OR3
	Transplant outdoors	Jan 31	Jan 16 – Feb 13	Colorado State4
	Plant for fall	Sep 13 – Oct 11	Aug 29 – Oct 21	Texas A&M (E-502)5
Cucumbers	Start indoors	Jan 3	Dec 19 – Jan 16	Oregon State, central OR3
	Transplant outdoors	Jan 24	Jan 9 – Feb 6	Oregon State, central OR3
	Sow outdoors	Jan 17	Jan 2 – Jan 30	Colorado State4
	Plant for fall	Oct 11 – Oct 25	Sep 26 – Nov 4	Texas A&M (E-502)5
Zucchini	Start indoors	Jan 10	Dec 26 – Jan 23	Oregon State, central OR3
	Transplant outdoors	Jan 31	Jan 16 – Feb 13	Oregon State, central OR3
	Sow outdoors	Jan 17	Jan 2 – Jan 30	Colorado State4
	Plant for fall	Sep 20 – Oct 11	Sep 5 – Oct 21	Texas A&M (E-502)5
Beans	Start indoors	Dec 27	Dec 12 – Jan 9	Oregon State, central OR3
	Transplant outdoors	Jan 24	Jan 9 – Feb 6	Oregon State, central OR3
	Sow outdoors	Jan 17	Jan 2 – Jan 30	Colorado State4
	Plant for fall	Oct 25 – Nov 8	Oct 10 – Nov 18	Texas A&M (E-502)5
	Plant for fall	Sep 13 – Sep 27	Aug 29 – Oct 7	Texas A&M (E-502)5
Peas	Start indoors	Nov 22	Nov 7 – Dec 5	Oregon State, central OR3
	Transplant outdoors	Dec 20	Dec 5 – Jan 2	Oregon State, central OR3
	Sow outdoors	Dec 20 – Jan 3	Dec 5 – Jan 16	Colorado State4
	Plant for fall	Oct 11 – Dec 20	Sep 26 – Dec 30	Texas A&M (E-502)5
Lettuce	Start indoors	Nov 29	Nov 14 – Dec 12	Oregon State, central OR3
	Transplant outdoors	Jan 3	Dec 19 – Jan 16	Oregon State, central OR3
	Sow outdoors	Dec 20 – Jan 3	Dec 5 – Jan 16	Colorado State4
	Plant for fall	Sep 27 – Oct 25	Sep 12 – Nov 4	Texas A&M (E-502)5
Carrots	Sow outdoors	Jan 3 – Jan 17	Dec 19 – Jan 30	Colorado State4
Carrots	Plant for fall	Sep 27 – Oct 11	Sep 12 – Oct 21	Texas A&M (E-502)5
Onions	Start indoors	Sep 27	Sep 12 – Oct 10	Oregon State, central OR3
	Transplant outdoors	Dec 6	Nov 21 – Dec 19	Oregon State, central OR3
	Sow outdoors	Dec 20 – Jan 3	Dec 5 – Jan 16	Colorado State4
	Plant for fall	Oct 25 – Nov 8	Oct 10 – Nov 18	Texas A&M (E-502)5
Garlic	Plant for fall	Jan 10 – Jan 17	Dec 26 – Jan 27	Wisconsin6
Potatoes	Sow outdoors	Jan 3 – Jan 17	Dec 19 – Jan 30	Colorado State4
Potatoes	Plant for fall	Sep 13 – Sep 27	Aug 29 – Oct 7	Texas A&M (E-502)5
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.
Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.
University of Wisconsin–Madison Division of Extension, Wisconsin Horticulture, Garlic, Allium sativum, Rev: 10/2023. Retrieved 2026-11-02.

Zone 10a

When to plant in zone 10a

Sources

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First, I check for frost

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