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Frost dates and planting calendar for Kingman, Arizona

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

USDA hardiness zone
8b[1]
Median last spring frost
Apr 2[2]
Median first fall frost
Nov 11[3]
Growing season, median
220 days[4]

Kingman, Arizona is in USDA hardiness zone 8b[1]. The median last spring frost is April 2 at the nearby NOAA airport station[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Mar 8, half of years Apr 2, 1 in 10 years after Apr 21Last frostmedian Apr 2First fall frost: 9 in 10 years before Nov 24, half of years Nov 11, 1 in 10 years before Oct 26First frostmedian Nov 11Frost riskHardyHardy vegetables: plant Mar 5 to Mar 19Mar 5 to Mar 19Semi-hardySemi-hardy vegetables: plant Mar 19 to Apr 2Mar 19 to Apr 2TenderTender vegetables: plant around Apr 2around Apr 2Very tenderVery tender vegetables: plant from Apr 16from Apr 16
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)[7]. Exact dates are in the tables below.

The frost dates here come from NOAA climate normals for the Kingman Mohave County Airport station, using records from 1991 to 2020[5]. In half of years the last spring frost comes after April 2, and in 1 of 10 years it comes after April 21[2]. In half of years the first fall frost comes before November 11, and in 1 of 10 years it comes before October 26[3]. These are odds from past records and not a forecast, so any year can be earlier or later[5]. At this station the low reached 32°F or colder in 100% of years[6].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after March 8 after April 2 after April 21
First fall frost (32°F)[3] before October 26 before November 11 before November 24
  • Hard freeze (28°F): median last spring date March 6, median first fall date November 22[8].
  • Frost-free growing season: at least 195 days in 9 of 10 years, 220 days in half of years and 249 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[6].
  • Weather station: Kingman Mohave County Airport (USW00093167), 5.2 miles from the city center, 3,420 feet, 19 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension's planting guide was written for Colorado, so GardenFacts applies its rules to Kingman's NOAA median last frost of April 2[7]. Hardy vegetables such as broccoli, lettuce, peas and spinach can go in as early as 2 to 4 weeks before that date, which works out to March 5 to March 19[7]. Semi-hardy vegetables such as beets, carrots and potatoes can go in as early as 2 weeks before the median last frost, which is March 19[9]. Tender vegetables such as snap beans and sweet corn can be planted from seed around April 2[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 April 16[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 2) is March 5 to March 19[7]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 2) is March 19, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 2[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 2), is April 16[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 5 May 9 (from transplants)
Cabbage (hardy)[12] Mar 5 May 29 (from transplants)
Kohlrabi (hardy)[12] Mar 5 Apr 24
Lettuce (hardy)[12] Mar 5 May 4
Onions (hardy)[12] Mar 5 Jun 23
Peas (hardy)[12] Mar 5 May 9
Radishes (hardy)[12] Mar 5 Apr 4
Spinach (hardy)[12] Mar 5 Apr 14
Turnips (hardy)[12] Mar 5 Apr 24
Beets (semi-hardy)[12] Mar 19 May 18
Carrots (semi-hardy)[12] Mar 19 May 28
Cauliflower (semi-hardy)[12] Mar 19 not listed
Parsnips (semi-hardy)[12] Mar 19 May 28
Potatoes (semi-hardy)[12] Mar 19 Jul 22
Swiss chard (semi-hardy)[12] Mar 19 May 18
Snap beans (tender)[12] Apr 2 Jun 1
Sweet corn (tender)[12] Apr 2 Jun 1
Cucumbers (tender)[12] Apr 2 May 27
Summer squash (tender)[12] Apr 2 May 22
Cantaloupe (very tender)[12] Apr 16 Jul 10
Eggplant (very tender)[12] Apr 16 Jun 15 (from transplants)
Peppers (very tender)[12] Apr 16 Jun 25 (from transplants)
Tomatoes (very tender)[12] Apr 16 Jun 20 (from transplants)
Winter squash (very tender)[12] Apr 16 Jul 25
Watermelon (very tender)[12] Apr 16 Jul 10
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 8b means the average coldest night of the winter was 15°F to 20°F over 1991 to 2020, based on the 2023 USDA map[1]. The zone does not describe frost dates or summer heat[14]. Kingman overlaps 2 ZIP code areas, and 100% of the city's land area lies in areas rated zone 8b[15].

Zone 8b: average annual extreme minimum temperature 15°F to 20°F (1991 to 2020)[1]. Modeled value at the city center: 17.1°F[1].

Share of the city's land area by ZIP code zone: zone 8b 100%[15].

All towns in zone 8b and what zone 8b means

Zone by ZIP code
ZIP code Zone Coldest night range
86401[15] 8b 15 to 20°F
86409[15] 8b 15 to 20°F

Questions people ask

What growing zone is Kingman, Arizona?
The 2023 USDA map puts the center of Kingman in zone 8b[1]. All of the city's land area is in ZIP code areas rated 8b[15].
When is the last frost in Kingman?
The median last spring frost is April 2, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after April 21[2].
When to plant tomatoes in Kingman?
CSU Extension says tomatoes typically wait 2 or more weeks after the average last spring frost[11]. Using the median last frost, the earliest start is April 16[11].
When is the first frost in Kingman?
The median first fall frost is November 11, so in half of years it comes before that date[3]. In 1 of 10 years it comes before October 26[3].
How long is the growing season in Kingman?
The growing season is at least 220 days in half of years[4]. It is at least 195 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Kingman, Arizona in zone 8b. Zone 8b means an average annual extreme minimum temperature of 15°F to 20°F over 1991 to 2020. The map's modeled value at the city center is 17.1°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 March 8, in half of years after April 2, and in 1 of 10 years after April 21 (NOAA 1991 to 2020 normals). The median last frost date is April 2. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before October 26, in half of years before November 11, and in 9 of 10 years before November 24 (NOAA 1991 to 2020 normals). The median first frost date is November 11. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 195 days in 9 of 10 years, at least 220 days in half of years, and at least 249 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Kingman Mohave County Airport weather station (USW00093167), 5.2 miles from the center of Kingman at 3,420 feet, using 19 years of records from 1991 to 2020. NOAA Climate Normals 1991-2020
  6. 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
  7. 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
  8. Hard freeze (28°F) at this station: the median last spring date is March 6 and the median first fall date is November 22. 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. Kingman, Arizona overlaps 2 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 8b. 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.