Saint Helens, OR planting zone & frost dates

Saint Helens is in USDA hardiness zone 8b. The last spring frost usually comes around April 18 and the first fall frost around November 7, for a growing season of about 201 days.

USDA hardiness zone8bavg. extreme winter low 15°F to 20°F

Average last spring frostApril 1890% chance of no frost after May 26

Average first fall frostNovember 710% chance of frost by October 21

Growing season201 daysfrost-free days in an average year

Planting calendar for Saint Helens

Dates are counted from the average last spring frost (April 18) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.

Crop	When
Tomatoes	Start seeds indoors: Feb 21 – Mar 7 Transplant outdoors: Apr 25 – May 2
Peppers	Start seeds indoors: Feb 7 – Feb 21 Transplant outdoors: May 2 – May 9
Eggplant	Start seeds indoors: Feb 7 – Feb 21 Transplant outdoors: May 2 – May 9
Broccoli	Start seeds indoors: Feb 7 – Feb 21 Transplant outdoors: Mar 21 – Apr 4
Cabbage	Start seeds indoors: Feb 7 – Feb 21 Transplant outdoors: Mar 21 – Apr 4
Onions (sets)	Plant outdoors: Mar 21 – Apr 4
Peas	Sow outdoors: Mar 7 – Mar 21
Spinach	Sow outdoors: Mar 7 – Mar 21
Lettuce	Sow outdoors: Mar 21 – Apr 4
Carrots	Sow outdoors: Mar 21 – Apr 4
Potatoes	Plant outdoors: Mar 21 – Apr 4
Beans	Sow outdoors: Apr 25 – May 2
Sweet corn	Sow outdoors: Apr 25 – May 2
Cucumbers	Sow outdoors: Apr 25 – May 2
Squash & zucchini	Sow outdoors: Apr 25 – May 2
Basil	Start seeds indoors: Mar 7 – Mar 21 Transplant outdoors: Apr 25 – May 2

Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 12 (8 weeks before the average first fall frost on Nov 7).

Useful for zone 8b gardens

Seed starting kit with dome — to start seeds indoors before the last frost
LED grow light for seedlings — stops leggy seedlings
Frost cloth / plant covers — for late spring and early fall frosts
Soil thermometer — warm-season crops need soil above 60°F

As an Amazon Associate, FrostZoneMap earns from qualifying purchases, at no extra cost to you.

Frost risk in detail

	90% chance	50% chance	10% chance
Last 32°F frost in spring is after	Mar 20	Apr 18	May 26
First 32°F frost in fall is before	Nov 26	Nov 7	Oct 21

How to read it: in spring there is a 10% chance of a frost after May 26, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 21. A hard freeze (28°F) usually ends around March 24.

Hardiness zone by ZIP code in Saint Helens

97051 zone 8b

Nearby cities

Bethany zone 8b, last frost Apr 16
Oak Hills zone 8b, last frost Feb 11
Cedar Mill zone 8b, last frost Feb 11
Portland zone 9a, last frost Feb 25
Aloha zone 9a, last frost Feb 11
Beaverton zone 9a, last frost Feb 11
Hillsboro zone 8b, last frost Apr 16
Cornelius zone 8b, last frost Apr 16

All cities in Oregon → · Other zone 8b cities →

Questions

What growing zone is Saint Helens, OR?

Saint Helens is in USDA Plant Hardiness Zone 8b (average extreme winter low 15°F to 20°F), according to the USDA 2023 map.

When is the last frost in Saint Helens?

The average last spring frost (32°F) in Saint Helens is April 18. There is still a 10% chance of frost until May 26.

When can I plant tomatoes in Saint Helens?

Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 25 – May 2. Start seeds indoors 6–8 weeks before the last frost.

Frost dates: NOAA U.S. Climate Normals 1991–2020, station Saint Helens Rfd, OR (USC00357466), 5.4 km (3.4 mi) from the city center, elevation 82 m, based on 16 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.