Evanston, WY planting zone & frost dates

Evanston is in USDA hardiness zone 5a. The last spring frost usually comes around June 12 and the first fall frost around September 12, for a growing season of about 90 days.

USDA hardiness zone5aavg. extreme winter low -20°F to -15°F

Average last spring frostJune 1290% chance of no frost after July 2

Average first fall frostSeptember 1210% chance of frost by August 26

Growing season90 daysfrost-free days in an average year

Planting calendar for Evanston

Dates are counted from the average last spring frost (June 12) 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: Apr 17 – May 1 Transplant outdoors: Jun 19 – Jun 26
Peppers	Start seeds indoors: Apr 3 – Apr 17 Transplant outdoors: Jun 26 – Jul 3
Eggplant	Start seeds indoors: Apr 3 – Apr 17 Transplant outdoors: Jun 26 – Jul 3
Broccoli	Start seeds indoors: Apr 3 – Apr 17 Transplant outdoors: May 15 – May 29
Cabbage	Start seeds indoors: Apr 3 – Apr 17 Transplant outdoors: May 15 – May 29
Onions (sets)	Plant outdoors: May 15 – May 29
Peas	Sow outdoors: May 1 – May 15
Spinach	Sow outdoors: May 1 – May 15
Lettuce	Sow outdoors: May 15 – May 29
Carrots	Sow outdoors: May 15 – May 29
Potatoes	Plant outdoors: May 15 – May 29
Beans	Sow outdoors: Jun 19 – Jun 26
Sweet corn	Sow outdoors: Jun 19 – Jun 26
Cucumbers	Sow outdoors: Jun 19 – Jun 26
Squash & zucchini	Sow outdoors: Jun 19 – Jun 26
Basil	Start seeds indoors: May 1 – May 15 Transplant outdoors: Jun 19 – Jun 26

Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Jul 18 (8 weeks before the average first fall frost on Sep 12).

Useful for zone 5a 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
Cold frame / mini greenhouse — adds weeks to a short season

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Frost risk in detail

	90% chance	50% chance	10% chance
Last 32°F frost in spring is after	May 26	Jun 12	Jul 2
First 32°F frost in fall is before	Sep 25	Sep 12	Aug 26

How to read it: in spring there is a 10% chance of a frost after July 2, so that is a safe date for tender plants. In fall there is a 10% chance of frost before August 26. A hard freeze (28°F) usually ends around May 24.

Hardiness zone by ZIP code in Evanston

82930 zone 5a
82931 zone 5a

Nearby cities

Rock Springs zone 5a, last frost May 24
Jackson zone 4b, last frost Jun 20
Riverton zone 4b, last frost May 12
Casper zone 5a, last frost May 10
Sheridan zone 5a, last frost May 21
Laramie zone 4a, last frost Jun 7
Cheyenne zone 5b, last frost May 14
Gillette zone 5a, last frost May 15

All cities in Wyoming → · Other zone 5a cities →

Questions

What growing zone is Evanston, WY?

Evanston is in USDA Plant Hardiness Zone 5a (average extreme winter low -20°F to -15°F), according to the USDA 2023 map.

When is the last frost in Evanston?

The average last spring frost (32°F) in Evanston is June 12. There is still a 10% chance of frost until July 2.

When can I plant tomatoes in Evanston?

Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jun 19 – Jun 26. Start seeds indoors 6–8 weeks before the last frost.

Frost dates: NOAA U.S. Climate Normals 1991–2020, station Evanston 1 E, WY (USC00483100), 1.1 km (0.7 mi) from the city center, elevation 2080 m, based on 24 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.