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Frost dates and planting calendar for Logan, Utah

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 8[2]
Median first fall frost
Oct 2[3]
Growing season, median
145 days[4]

Logan, Utah is in USDA hardiness zone 6a[1]. NOAA records show the median last spring frost is May 8[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 25, half of years May 8, 1 in 10 years after Jun 2Last frostmedian May 8First fall frost: 9 in 10 years before Oct 15, half of years Oct 2, 1 in 10 years before Sep 18First frostmedian Oct 2Frost riskHardyHardy vegetables: plant Apr 10 to Apr 24Apr 10 to Apr 24Semi-hardySemi-hardy vegetables: plant Apr 24 to May 8Apr 24 to May 8TenderTender vegetables: plant around May 8around May 8Very tenderVery tender vegetables: plant from May 22from May 22
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 dates are odds from NOAA records for 1991 to 2020, not a forecast[5]. In half of years the last spring frost comes after May 8, and in 1 of 10 years it comes after June 2[2]. In half of years the first fall frost comes before October 2, and in 1 of 10 years it comes before September 18[3]. The numbers come from the Logan Radio Kvnu weather station, using 29 years of records[5].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 25 after May 8 after June 2
First fall frost (32°F)[3] before September 18 before October 2 before October 15
  • Hard freeze (28°F): median last spring date April 23, median first fall date October 14[7].
  • Frost-free growing season: at least 121 days in 9 of 10 years, 145 days in half of years and 164 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: Logan Radio Kvnu (USC00425182), 0.8 miles from the city center, 4,475 feet, 29 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension's planting guide was written for Colorado, so treat the dates as a starting point for Logan[6]. Hardy vegetables such as peas, lettuce and spinach can go in as early as 2 to 4 weeks before the median last frost, which is April 10 to April 24[6]. Semi-hardy vegetables such as potatoes and carrots can go in as early as 2 weeks before the median last frost, which is April 24[9]. Tender vegetables such as snap beans and sweet corn can be planted from seed around the median last frost date, May 8[10]. Very tender vegetables such as tomatoes and peppers typically wait 2 or more weeks after it, so the earliest start is May 22[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (May 8) is April 10 to April 24[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (May 8) is April 24, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, May 8[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (May 8), is May 22[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Apr 10 Jun 14 (from transplants)
Cabbage (hardy)[12] Apr 10 Jul 4 (from transplants)
Kohlrabi (hardy)[12] Apr 10 May 30
Lettuce (hardy)[12] Apr 10 Jun 9
Onions (hardy)[12] Apr 10 Jul 29
Peas (hardy)[12] Apr 10 Jun 14
Radishes (hardy)[12] Apr 10 May 10
Spinach (hardy)[12] Apr 10 May 20
Turnips (hardy)[12] Apr 10 May 30
Beets (semi-hardy)[12] Apr 24 Jun 23
Carrots (semi-hardy)[12] Apr 24 Jul 3
Cauliflower (semi-hardy)[12] Apr 24 not listed
Parsnips (semi-hardy)[12] Apr 24 Jul 3
Potatoes (semi-hardy)[12] Apr 24 Aug 27
Swiss chard (semi-hardy)[12] Apr 24 Jun 23
Snap beans (tender)[12] May 8 Jul 7
Sweet corn (tender)[12] May 8 Jul 7
Cucumbers (tender)[12] May 8 Jul 2
Summer squash (tender)[12] May 8 Jun 27
Cantaloupe (very tender)[12] May 22 Aug 15
Eggplant (very tender)[12] May 22 Jul 21 (from transplants)
Peppers (very tender)[12] May 22 Jul 31 (from transplants)
Tomatoes (very tender)[12] May 22 Jul 26 (from transplants)
Winter squash (very tender)[12] May 22 Aug 30
Watermelon (very tender)[12] May 22 Aug 15
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 2023 map puts the center of Logan in zone 6a, which means an average coldest night of -10°F to -5°F[1]. The zone is based on winter lows, not on summer heat or frost dates[14]. By land area, all of Logan lies in ZIP code areas rated zone 6a[15].

Zone 6a: average annual extreme minimum temperature -10°F to -5°F (1991 to 2020)[1]. Modeled value at the city center: -8.6°F[1].

Share of the city's land area by ZIP code zone: zone 6a 100%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
84321[15] 6a -10 to -5°F
84341[15] 6a -10 to -5°F
84335[15] 6a -10 to -5°F
84339[15] 6a -10 to -5°F

Questions people ask

What growing zone is Logan, Utah?
Logan is in USDA zone 6a on the 2023 map[1]. All of the city's land area lies in ZIP code areas rated 6a[15].
When is the last frost in Logan?
The median last spring frost is May 8, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after June 2[2].
When is the first frost in Logan?
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 18[3].
When to plant tomatoes in Logan?
CSU Extension lists tomatoes as very tender and typically planted 2 or more weeks after the average last frost[11]. Using the median last frost, the earliest start is May 22[11].
How long is the growing season in Logan?
The growing season is at least 145 days in half of years[4]. It is at least 121 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Logan, Utah 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 8.6°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 April 25, in half of years after May 8, and in 1 of 10 years after June 2 (NOAA 1991 to 2020 normals). The median last frost date is May 8. 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 2, and in 9 of 10 years before October 15 (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 121 days in 9 of 10 years, at least 145 days in half of years, and at least 164 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Logan Radio Kvnu weather station (USC00425182), 0.8 miles from the center of Logan at 4,475 feet, using 29 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 April 23 and the median first fall date is October 14. 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. Logan, Utah overlaps 4 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 6a. 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.