GardenFacts

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Frost dates and planting calendar for Cheyenne, Wyoming

Updated October 30, 2026. Based on USDA, NOAA and Colorado State University Extension data. Published by Humblebee.

USDA hardiness zone
5b[1]
Median last spring frost
May 12[2]
Median first fall frost
Oct 1[3]
Growing season, median
141 days[4]

The center of Cheyenne, Wyoming is in USDA hardiness zone 5b[1]. The median last spring frost at the Cheyenne weather station is May 12[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after May 1, half of years May 12, 1 in 10 years after May 26Last frostmedian May 12First fall frost: 9 in 10 years before Oct 14, half of years Oct 1, 1 in 10 years before Sep 18First frostmedian Oct 1Frost riskHardyHardy vegetables: plant Apr 14 to Apr 28Apr 14 to Apr 28Semi-hardySemi-hardy vegetables: plant Apr 28 to May 12Apr 28 to May 12TenderTender vegetables: plant around May 12around May 12Very tenderVery tender vegetables: plant from May 26from May 26
Shaded: the span between the dates frost passes in 9 of 10 years and 1 of 10 years[2][3]. Green: planting windows from the CSU rules applied to the median last frost (GardenFacts calculation)[6]. Exact dates are in the tables below.

These frost dates come from NOAA climate normals for the Cheyenne weather station, using records from 1991 to 2020[5]. They are odds, not a forecast. In half of years the last spring frost comes after May 12, and in 1 of 10 years it comes after May 26[2]. In half of years the first fall frost comes before October 1, and in 1 of 10 years it comes before September 18[3]. Any year can be earlier or later.

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after May 1 after May 12 after May 26
First fall frost (32°F)[3] before September 18 before October 1 before October 14
  • Hard freeze (28°F): median last spring date May 2, median first fall date October 11[7].
  • Frost-free growing season: at least 122 days in 9 of 10 years, 141 days in half of years and 158 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 100% of years and 28°F or colder in 100% of years[8].
  • Weather station: Cheyenne (USW00024018), 1.8 miles from the city center, 6,128 feet, 30 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension groups vegetables by how well they handle cold, and its guide was written for Colorado[6]. Hardy vegetables such as lettuce, peas and spinach can go in as early as 2 to 4 weeks before the median last frost, which works out to April 14 to April 28 in Cheyenne[6]. Semi-hardy vegetables such as carrots and potatoes can go in as early as 2 weeks before the median last frost, from April 28 up to May 12[9]. Tender vegetables such as snap beans and sweet corn can be planted from seed around May 12[10]. Very tender vegetables such as tomatoes and peppers typically wait 2 or more weeks after the median last frost, so the earliest start is May 26[11]. These dates are a GardenFacts calculation from the CSU rules, using the median last frost[6][9][10][11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (May 12) is April 14 to April 28[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (May 12) is April 28, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, May 12[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (May 12), is May 26[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Apr 14 Jun 18 (from transplants)
Cabbage (hardy)[12] Apr 14 Jul 8 (from transplants)
Kohlrabi (hardy)[12] Apr 14 Jun 3
Lettuce (hardy)[12] Apr 14 Jun 13
Onions (hardy)[12] Apr 14 Aug 2
Peas (hardy)[12] Apr 14 Jun 18
Radishes (hardy)[12] Apr 14 May 14
Spinach (hardy)[12] Apr 14 May 24
Turnips (hardy)[12] Apr 14 Jun 3
Beets (semi-hardy)[12] Apr 28 Jun 27
Carrots (semi-hardy)[12] Apr 28 Jul 7
Cauliflower (semi-hardy)[12] Apr 28 not listed
Parsnips (semi-hardy)[12] Apr 28 Jul 7
Potatoes (semi-hardy)[12] Apr 28 Aug 31
Swiss chard (semi-hardy)[12] Apr 28 Jun 27
Snap beans (tender)[12] May 12 Jul 11
Sweet corn (tender)[12] May 12 Jul 11
Cucumbers (tender)[12] May 12 Jul 6
Summer squash (tender)[12] May 12 Jul 1
Cantaloupe (very tender)[12] May 26 Aug 19
Eggplant (very tender)[12] May 26 Jul 25 (from transplants)
Peppers (very tender)[12] May 26 Aug 4 (from transplants)
Tomatoes (very tender)[12] May 26 Jul 30 (from transplants)
Winter squash (very tender)[12] May 26 Sep 3
Watermelon (very tender)[12] May 26 Aug 19
Spacing, depth and soil temperature (CSU Extension)
Vegetable Min. soil temp Depth Spacing Days to harvest
Broccoli[13] 40°F 1/2 in 18 in 65
Cabbage[13] 40°F 1/2 in 18 in 85
Kohlrabi[13] 40°F 1/2 in 7-9 in 50
Lettuce[13] 35°F 1/4 in 7-9 in 60
Onions[13] 35°F 1/4 in (seed), 1-2 in (sets) 4-6 in 110
Peas[13] 40°F 1 in 4-6 in 65
Radishes[13] 40°F 1/2 in 2-3 in 30
Spinach[13] 40°F 1/2 in 4-6 in 40
Turnips[13] 40°F 1/2 in 4-6 in 50
Beets[13] 40°F 3/4-1 in 4-6 in 60
Carrots[13] 40°F 1/4 in 2-3 in 70
Cauliflower[13] 40°F 1/2 in 18 in –
Parsnips[13] 35°F 1/2 in 5-6 in 70
Potatoes[13] 45°F – – 125
Swiss chard[13] 40°F 1 in 7-9 in 60
Snap beans[13] 55°F 1-1 1/2 in 6 in 60
Sweet corn[13] 50°F 1-1 1/2 in 12 x 30 in or 9 x 36 in 60-90
Cucumbers[13] 60°F 1 in 6 in trellised, 24-36 in untrellised 55
Summer squash[13] 60°F 1-1 1/2 in 36-48 in 50
Cantaloupe[13] 60°F 1-1 1/2 in 36-48 in 85
Eggplant[13] 60°F 1/4 in 18-24 in 60
Peppers[13] 60°F 1/4 in 15-18 in 70
Tomatoes[13] 50°F 1/4 in 24 in trellised 65
Winter squash[13] 60°F 1-1 1/2 in 36-48 in 100
Watermelon[13] 60°F 1-1 1/2 in 36-48 in 85

Hardiness zone

Zone 5b means the average coldest night of the winter was -15°F to -10°F over 1991 to 2020[1]. The zone is based on winter cold, not on summer heat or frost dates[14]. All of Cheyenne's land area, across 3 ZIP code areas, is in zone 5b[15].

Zone 5b: average annual extreme minimum temperature -15°F to -10°F (1991 to 2020)[1]. Modeled value at the city center: -13.6°F[1].

Share of the city's land area by ZIP code zone: zone 5b 100%[15].

All towns in zone 5b and what zone 5b means

Zone by ZIP code
ZIP code Zone Coldest night range
82007[15] 5b -15 to -10°F
82001[15] 5b -15 to -10°F
82009[15] 5b -15 to -10°F

Questions people ask

What growing zone is Cheyenne, Wyoming?
The center of Cheyenne is in USDA zone 5b on the 2023 map[1]. All of the city's land area is in ZIP code areas rated 5b[15].
When is the last frost in Cheyenne?
The median last spring frost is May 12, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after May 26[2].
When to plant tomatoes in Cheyenne?
CSU Extension says very tender vegetables like tomatoes typically wait 2 or more weeks after the average last spring frost[11]. Using the median last frost, the earliest start is May 26[11].
When is the first frost in Cheyenne?
The median first fall frost is October 1, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before September 18[3].
How long is the growing season in Cheyenne?
The growing season is at least 141 days in half of years[4]. It is at least 122 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Cheyenne, Wyoming in zone 5b. Zone 5b means an average annual extreme minimum temperature of -15°F to -10°F over 1991 to 2020. The map's modeled value at the city center is minus 13.6°F. USDA zone map 2023 (PRISM, OSU)
  2. Last spring frost (32°F) at this station: in 9 of 10 years the last frost comes after May 1, in half of years after May 12, and in 1 of 10 years after May 26 (NOAA 1991 to 2020 normals). The median last frost date is May 12. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before September 18, in half of years before October 1, and in 9 of 10 years before October 14 (NOAA 1991 to 2020 normals). The median first frost date is October 1. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 122 days in 9 of 10 years, at least 141 days in half of years, and at least 158 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Cheyenne weather station (USW00024018), 1.8 miles from the center of Cheyenne at 6,128 feet, using 30 years of records from 1991 to 2020. NOAA Climate Normals 1991-2020
  6. Colorado State University Extension's vegetable planting guide (written for Colorado) groups broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips as hardy vegetables, with this rule: as early as 2-4 weeks before the average last... CSU Extension GardenNotes #720
  7. Hard freeze (28°F) at this station: the median last spring date is May 2 and the median first fall date is October 11. NOAA Climate Normals 1991-2020
  8. At this station the low reached 32°F or colder in 100% of years from 1991 to 2020, and 28°F or colder in 100% of years. NOAA Climate Normals 1991-2020
  9. Colorado State University Extension's vegetable planting guide (written for Colorado) groups beets, carrots, cauliflower, parsnips, potatoes, Swiss chard as semi-hardy vegetables, with this rule: as early as 0-2 weeks before the average last spring frost.... CSU Extension GardenNotes #720
  10. Colorado State University Extension's vegetable planting guide (written for Colorado) groups snap beans, sweet corn, cucumbers, summer squash as tender vegetables, with this rule: from seed around the average last spring frost; cucumber and summer squash... CSU Extension GardenNotes #720
  11. Colorado State University Extension's vegetable planting guide (written for Colorado) groups cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon as very tender vegetables, with this rule: typically 2 or more weeks after the average last... CSU Extension GardenNotes #720
  12. GardenFacts calculation: earliest planting date plus CSU days to harvest (table on this page), from the station's median last frost. NOAA Climate Normals 1991-2020
  13. CSU Extension vegetable table: soil temperature, depth, spacing, days to harvest (table on this page). CSU Extension GardenNotes #720
  14. USDA hardiness zones are based on the average annual extreme minimum winter temperature (the coldest night of each winter, averaged over 1991 to 2020 for the 2023 map), not on summer heat or frost dates. Each zone spans 10°F and each half zone (a or b)... USDA Plant Hardiness Zone Map
  15. Cheyenne, Wyoming overlaps 3 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 5b. USDA zone map 2023 (PRISM, OSU)

Frost dates are probabilities from 1991 to 2020 weather records at one NOAA station, not a forecast. Any year can be earlier or later. The hardiness zone describes the average coldest winter night, not frost dates or summer heat. Spots inside the city can differ (ZIP table). Planting rules come from Colorado State University Extension's guide, written for Colorado. A local extension office may give dates tuned to the area. Planting and harvest dates marked GardenFacts calculation are simple arithmetic from the facts above, not advice from the source.

Hardiness zone data: USDA Plant Hardiness Zone Map (2023), USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu, accessed October 30, 2026. This is not the official USDA map. Frost data: NOAA NCEI U.S. Climate Normals 1991-2020. Planting rules: Colorado State University Extension.