Sheridan, WY planting zone & frost dates

Sheridan is in USDA hardiness zone 5a. The last spring frost usually comes around May 21 and the first fall frost around September 23, for a growing season of about 123 days.

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

Average last spring frostMay 2190% chance of no frost after June 6

Average first fall frostSeptember 2310% chance of frost by September 9

Growing season123 daysfrost-free days in an average year

Planting calendar for Sheridan

Dates are counted from the average last spring frost (May 21) 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: Mar 26 – Apr 9 Transplant outdoors: May 28 – Jun 4
Peppers	Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Jun 4 – Jun 11
Eggplant	Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Jun 4 – Jun 11
Broccoli	Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Apr 23 – May 7
Cabbage	Start seeds indoors: Mar 12 – Mar 26 Transplant outdoors: Apr 23 – May 7
Onions (sets)	Plant outdoors: Apr 23 – May 7
Peas	Sow outdoors: Apr 9 – Apr 23
Spinach	Sow outdoors: Apr 9 – Apr 23
Lettuce	Sow outdoors: Apr 23 – May 7
Carrots	Sow outdoors: Apr 23 – May 7
Potatoes	Plant outdoors: Apr 23 – May 7
Beans	Sow outdoors: May 28 – Jun 4
Sweet corn	Sow outdoors: May 28 – Jun 4
Cucumbers	Sow outdoors: May 28 – Jun 4
Squash & zucchini	Sow outdoors: May 28 – Jun 4
Basil	Start seeds indoors: Apr 9 – Apr 23 Transplant outdoors: May 28 – Jun 4

Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Jul 29 (8 weeks before the average first fall frost on Sep 23).

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 7	May 21	Jun 6
First 32°F frost in fall is before	Oct 6	Sep 23	Sep 9

How to read it: in spring there is a 10% chance of a frost after June 6, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 9. A hard freeze (28°F) usually ends around May 7.

Hardiness zone by ZIP code in Sheridan

82801 zone 5a

Nearby cities

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

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

Questions

What growing zone is Sheridan, WY?

Sheridan 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 Sheridan?

The average last spring frost (32°F) in Sheridan is May 21. There is still a 10% chance of frost until June 6.

When can I plant tomatoes in Sheridan?

Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 28 – Jun 4. Start seeds indoors 6–8 weeks before the last frost.

Frost dates: NOAA U.S. Climate Normals 1991–2020, station Sheridan Co Ap, WY (USW00024029), 3.2 km (2.0 mi) from the city center, elevation 1202 m, based on 29 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.