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Frost dates and planting calendar for Pocatello, Idaho

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

USDA hardiness zone
6a[1]
Median last spring frost
May 16[2]
Median first fall frost
Oct 2[3]
Growing season, median
137 days[4]

Pocatello, Idaho sits in USDA hardiness zone 6a at the city center[1]. The median last spring frost is May 16, which means about half of years see a frost after that date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 30, half of years May 16, 1 in 10 years after Jun 6Last frostmedian May 16First fall frost: 9 in 10 years before Oct 18, half of years Oct 2, 1 in 10 years before Sep 14First frostmedian Oct 2Frost riskHardyHardy vegetables: plant Apr 18 to May 2Apr 18 to May 2Semi-hardySemi-hardy vegetables: plant May 2 to May 16May 2 to May 16TenderTender vegetables: plant around May 16around May 16Very tenderVery tender vegetables: plant from May 30from May 30
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 are odds from NOAA records for 1991 to 2020, not a forecast[5]. They come from the Pocatello 2NE weather station[5]. In half of years the last spring frost comes after May 16, in 9 of 10 years it comes after April 30, and in 1 of 10 years it comes after June 6[2]. In the fall, the median first frost is October 2, and in 1 of 10 years it comes before September 14[3]. Any year can be earlier or later than these dates[2].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 30 after May 16 after June 6
First fall frost (32°F)[3] before September 14 before October 2 before October 18
  • Hard freeze (28°F): median last spring date May 1, median first fall date October 13[7].
  • Frost-free growing season: at least 111 days in 9 of 10 years, 137 days in half of years and 162 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: Pocatello 2NE (USC00107208), 3.1 miles from the city center, 4,832 feet, 26 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension's planting guide was written for Colorado, so treat these dates as a starting point[6]. GardenFacts takes the NOAA median last frost of May 16 as the average last frost[6]. Hardy vegetables such as lettuce, peas and spinach can go in as early as 2 to 4 weeks before that date, which is April 18 to May 2[6]. Semi-hardy vegetables such as carrots and potatoes can go in as early as May 2, up to the median date itself[9]. Tender vegetables such as snap beans and sweet corn can be seeded around May 16[10]. Very tender vegetables such as tomatoes and peppers typically start 2 or more weeks after the median last frost, so the earliest start is May 30[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (May 16) is April 18 to May 2[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (May 16) is May 2, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, May 16[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (May 16), is May 30[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Apr 18 Jun 22 (from transplants)
Cabbage (hardy)[12] Apr 18 Jul 12 (from transplants)
Kohlrabi (hardy)[12] Apr 18 Jun 7
Lettuce (hardy)[12] Apr 18 Jun 17
Onions (hardy)[12] Apr 18 Aug 6
Peas (hardy)[12] Apr 18 Jun 22
Radishes (hardy)[12] Apr 18 May 18
Spinach (hardy)[12] Apr 18 May 28
Turnips (hardy)[12] Apr 18 Jun 7
Beets (semi-hardy)[12] May 2 Jul 1
Carrots (semi-hardy)[12] May 2 Jul 11
Cauliflower (semi-hardy)[12] May 2 not listed
Parsnips (semi-hardy)[12] May 2 Jul 11
Potatoes (semi-hardy)[12] May 2 Sep 4
Swiss chard (semi-hardy)[12] May 2 Jul 1
Snap beans (tender)[12] May 16 Jul 15
Sweet corn (tender)[12] May 16 Jul 15
Cucumbers (tender)[12] May 16 Jul 10
Summer squash (tender)[12] May 16 Jul 5
Cantaloupe (very tender)[12] May 30 Aug 23
Eggplant (very tender)[12] May 30 Jul 29 (from transplants)
Peppers (very tender)[12] May 30 Aug 8 (from transplants)
Tomatoes (very tender)[12] May 30 Aug 3 (from transplants)
Winter squash (very tender)[12] May 30 Sep 7
Watermelon (very tender)[12] May 30 Aug 23
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

The USDA map puts the center of Pocatello in zone 6a, which means an average coldest night of -10°F to -5°F over 1991 to 2020[1]. A zone is based on the coldest winter night, not on summer heat or frost dates[14]. Pocatello overlaps 4 ZIP code areas, and by land area 65% lies in zone 6a areas and 35% in zone 6b areas[15].

Zone 6a: average annual extreme minimum temperature -10°F to -5°F (1991 to 2020)[1]. Modeled value at the city center: -7.8°F[1].

Share of the city's land area by ZIP code zone: zone 6a 65%, zone 6b 35%[15].

All towns in zone 6a and what zone 6a means

Zone by ZIP code
ZIP code Zone Coldest night range
83204[15] 6a -10 to -5°F
83201[15] 6b -5 to 0°F
83202[15] 6a -10 to -5°F
83209[15] 6a -10 to -5°F

Questions people ask

What growing zone is Pocatello, Idaho?
The 2023 USDA map puts the center of Pocatello in zone 6a[1]. By land area, 35% of the city lies in ZIP code areas rated zone 6b[15].
When is the last frost in Pocatello?
The median last spring frost is May 16, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after June 6[2].
When is the first frost in Pocatello?
The median first fall frost is October 2, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before September 14[3].
When to plant tomatoes in Pocatello?
CSU Extension typically starts tomatoes 2 or more weeks after the average last spring frost[11]. Using the median last frost, the earliest start is May 30[11].
How long is the growing season in Pocatello?
The season between the last spring and first fall frost is at least 137 days in half of years[4]. It is at least 111 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Pocatello, Idaho in zone 6a. Zone 6a means an average annual extreme minimum temperature of -10°F to -5°F over 1991 to 2020. The map's modeled value at the city center is minus 7.8°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 April 30, in half of years after May 16, and in 1 of 10 years after June 6 (NOAA 1991 to 2020 normals). The median last frost date is May 16. 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 14, in half of years before October 2, and in 9 of 10 years before October 18 (NOAA 1991 to 2020 normals). The median first frost date is October 2. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 111 days in 9 of 10 years, at least 137 days in half of years, and at least 162 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Pocatello 2NE weather station (USC00107208), 3.1 miles from the center of Pocatello at 4,832 feet, using 26 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 1 and the median first fall date is October 13. 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. Pocatello, Idaho overlaps 4 ZIP code areas. By land area, 65% lies in ZIP code areas rated zone 6a, 35% lies in ZIP code areas rated zone 6b. 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.