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Frost dates and planting calendar for Jackson, Michigan

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 1[2]
Median first fall frost
Oct 14[3]
Growing season, median
164 days[4]

Jackson, Michigan is in USDA hardiness zone 6a[1]. The median last spring frost is May 1, which means the last frost comes after that date in half of years[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 16, half of years May 1, 1 in 10 years after May 18Last frostmedian May 1First fall frost: 9 in 10 years before Oct 28, half of years Oct 14, 1 in 10 years before Sep 30First frostmedian Oct 14Frost riskHardyHardy vegetables: plant Apr 3 to Apr 17Apr 3 to Apr 17Semi-hardySemi-hardy vegetables: plant Apr 17 to May 1Apr 17 to May 1TenderTender vegetables: plant around May 1around May 1Very tenderVery tender vegetables: plant from May 15from May 15
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, not promises. They come from NOAA 1991 to 2020 records at the Jackson Reynolds Field weather station[5]. In 9 of 10 years the last spring frost comes after April 16, and in 1 of 10 years it comes after May 18[2]. In the fall, the first frost comes before October 14 in half of years[3]. In 1 of 10 years it comes before September 30[3]. Any single 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 16 after May 1 after May 18
First fall frost (32°F)[3] before September 30 before October 14 before October 28
  • Hard freeze (28°F): median last spring date April 20, median first fall date October 28[7].
  • Frost-free growing season: at least 142 days in 9 of 10 years, 164 days in half of years and 187 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: Jackson Reynolds Field (USW00014833), 3.5 miles from the city center, 998 feet, 30 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, so these dates are a starting point for Jackson[6]. GardenFacts takes the median last frost, May 1, as the average last frost in CSU's rules[6]. Hardy vegetables such as broccoli, lettuce, peas and spinach can go in as early as 2 to 4 weeks before that date, which is April 3 to April 17[6]. Tender vegetables such as snap beans and sweet corn can start from seed around May 1[9]. 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 15[10]. The median first fall frost is October 14, and tender and very tender vegetables do not tolerate frost[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (May 1) is April 3 to April 17[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (May 1) is April 17, up to the median date itself[12]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, May 1[9]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (May 1), is May 15[10]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[13] Apr 3 Jun 7 (from transplants)
Cabbage (hardy)[13] Apr 3 Jun 27 (from transplants)
Kohlrabi (hardy)[13] Apr 3 May 23
Lettuce (hardy)[13] Apr 3 Jun 2
Onions (hardy)[13] Apr 3 Jul 22
Peas (hardy)[13] Apr 3 Jun 7
Radishes (hardy)[13] Apr 3 May 3
Spinach (hardy)[13] Apr 3 May 13
Turnips (hardy)[13] Apr 3 May 23
Beets (semi-hardy)[13] Apr 17 Jun 16
Carrots (semi-hardy)[13] Apr 17 Jun 26
Cauliflower (semi-hardy)[13] Apr 17 not listed
Parsnips (semi-hardy)[13] Apr 17 Jun 26
Potatoes (semi-hardy)[13] Apr 17 Aug 20
Swiss chard (semi-hardy)[13] Apr 17 Jun 16
Snap beans (tender)[13] May 1 Jun 30
Sweet corn (tender)[13] May 1 Jun 30
Cucumbers (tender)[13] May 1 Jun 25
Summer squash (tender)[13] May 1 Jun 20
Cantaloupe (very tender)[13] May 15 Aug 8
Eggplant (very tender)[13] May 15 Jul 14 (from transplants)
Peppers (very tender)[13] May 15 Jul 24 (from transplants)
Tomatoes (very tender)[13] May 15 Jul 19 (from transplants)
Winter squash (very tender)[13] May 15 Aug 23
Watermelon (very tender)[13] May 15 Aug 8
Spacing, depth and soil temperature (CSU Extension)
Vegetable Min. soil temp Depth Spacing Days to harvest
Broccoli[14] 40°F 1/2 in 18 in 65
Cabbage[14] 40°F 1/2 in 18 in 85
Kohlrabi[14] 40°F 1/2 in 7-9 in 50
Lettuce[14] 35°F 1/4 in 7-9 in 60
Onions[14] 35°F 1/4 in (seed), 1-2 in (sets) 4-6 in 110
Peas[14] 40°F 1 in 4-6 in 65
Radishes[14] 40°F 1/2 in 2-3 in 30
Spinach[14] 40°F 1/2 in 4-6 in 40
Turnips[14] 40°F 1/2 in 4-6 in 50
Beets[14] 40°F 3/4-1 in 4-6 in 60
Carrots[14] 40°F 1/4 in 2-3 in 70
Cauliflower[14] 40°F 1/2 in 18 in –
Parsnips[14] 35°F 1/2 in 5-6 in 70
Potatoes[14] 45°F – – 125
Swiss chard[14] 40°F 1 in 7-9 in 60
Snap beans[14] 55°F 1-1 1/2 in 6 in 60
Sweet corn[14] 50°F 1-1 1/2 in 12 x 30 in or 9 x 36 in 60-90
Cucumbers[14] 60°F 1 in 6 in trellised, 24-36 in untrellised 55
Summer squash[14] 60°F 1-1 1/2 in 36-48 in 50
Cantaloupe[14] 60°F 1-1 1/2 in 36-48 in 85
Eggplant[14] 60°F 1/4 in 18-24 in 60
Peppers[14] 60°F 1/4 in 15-18 in 70
Tomatoes[14] 50°F 1/4 in 24 in trellised 65
Winter squash[14] 60°F 1-1 1/2 in 36-48 in 100
Watermelon[14] 60°F 1-1 1/2 in 36-48 in 85

Hardiness zone

The 2023 USDA map puts Jackson in zone 6a, which means an average coldest night of the year between -10°F and -5°F over 1991 to 2020[1]. The zone is based on that coldest winter night, not on summer heat or frost dates[15]. Jackson overlaps 3 ZIP code areas, and by land area 100% lies in zone 6a[16].

Zone 6a: average annual extreme minimum temperature -10°F to -5°F (1991 to 2020)[1]. Modeled value at the city center: -7.9°F[1].

Share of the city's land area by ZIP code zone: zone 6a 100%[16].

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

Zone by ZIP code
ZIP code Zone Coldest night range
49203[16] 6a -10 to -5°F
49202[16] 6a -10 to -5°F
49201[16] 6a -10 to -5°F

Questions people ask

What growing zone is Jackson, Michigan?
The center of Jackson is in USDA zone 6a on the 2023 map[1]. All of the city's land area lies in ZIP code areas rated 6a[16].
When is the last frost in Jackson, Michigan?
The median last spring frost is May 1, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after May 18[2].
When to plant tomatoes in Jackson, Michigan?
CSU Extension says tomatoes typically go in 2 or more weeks after the average last spring frost[10]. Using the May 1 median, the earliest start is May 15[10]. CSU's guide was written for Colorado[10].
When is the first frost in Jackson, Michigan?
The median first fall frost is October 14, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before September 30[3].
How long is the growing season in Jackson, Michigan?
The growing season is at least 164 days in half of years[4]. It is at least 142 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Jackson, Michigan 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 7.9°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 16, in half of years after May 1, and in 1 of 10 years after May 18 (NOAA 1991 to 2020 normals). The median last frost date is May 1. 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 30, in half of years before October 14, and in 9 of 10 years before October 28 (NOAA 1991 to 2020 normals). The median first frost date is October 14. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 142 days in 9 of 10 years, at least 164 days in half of years, and at least 187 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Jackson Reynolds Field weather station (USW00014833), 3.5 miles from the center of Jackson at 998 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 April 20 and the median first fall date is October 28. 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 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
  10. 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
  11. Tender and very tender vegetables do not tolerate frost (CSU Extension). In Jackson the median first fall frost is October 14. CSU Extension GardenNotes #720
  12. 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
  13. 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
  14. CSU Extension vegetable table: soil temperature, depth, spacing, days to harvest (table on this page). CSU Extension GardenNotes #720
  15. 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
  16. Jackson, Michigan overlaps 3 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.