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Frost dates and planting calendar for Madison, Wisconsin

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 1[2]
Median first fall frost
Oct 9[3]
Growing season, median
161 days[4]

The center of Madison, Wisconsin sits in USDA hardiness zone 5b[1]. At the nearby NOAA weather station, the median last spring frost is May 1[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 18, half of years May 1, 1 in 10 years after May 17Last frostmedian May 1First fall frost: 9 in 10 years before Oct 24, half of years Oct 9, 1 in 10 years before Sep 26First frostmedian Oct 9Frost 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)[7]. Exact dates are in the tables below.

Frost dates here come from NOAA climate normals for the Uw Arboretum - Madison weather station, using records from 1991 to 2020[5]. In half of years the last spring frost comes after May 1, and in 1 of 10 years it comes after May 17[2]. In fall, the first frost comes before October 9 in half of years and before September 26 in 1 of 10 years[3]. These are chances from past weather, not a forecast for any one year. A hard freeze of 28°F has a median last spring date of April 20 and a median first fall date of October 20[6].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 18 after May 1 after May 17
First fall frost (32°F)[3] before September 26 before October 9 before October 24
  • Hard freeze (28°F): median last spring date April 20, median first fall date October 20[6].
  • Frost-free growing season: at least 140 days in 9 of 10 years, 161 days in half of years and 179 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: Uw Arboretum - Madison (USC00470273), 3.2 miles from the city center, 870 feet, 27 years of 1991 to 2020 records[5].

When to plant vegetables

The planting dates use Colorado State University Extension's vegetable guide, which was written for Colorado[7]. GardenFacts takes the NOAA median last frost of May 1 as the average last frost and counts from there[7]. Hardy crops like peas, lettuce and spinach can go in as early as April 3 to April 17[7]. Semi-hardy crops like beets, carrots and potatoes can go in as early as April 17, up to May 1[9]. Tender crops like snap beans and sweet corn go in from seed around May 1[10]. Very tender crops like tomatoes and peppers have an earliest start of May 15, typically 2 or more weeks after the median last 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[7]
  • 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[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, May 1[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (May 1), is May 15[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Apr 3 Jun 7 (from transplants)
Cabbage (hardy)[12] Apr 3 Jun 27 (from transplants)
Kohlrabi (hardy)[12] Apr 3 May 23
Lettuce (hardy)[12] Apr 3 Jun 2
Onions (hardy)[12] Apr 3 Jul 22
Peas (hardy)[12] Apr 3 Jun 7
Radishes (hardy)[12] Apr 3 May 3
Spinach (hardy)[12] Apr 3 May 13
Turnips (hardy)[12] Apr 3 May 23
Beets (semi-hardy)[12] Apr 17 Jun 16
Carrots (semi-hardy)[12] Apr 17 Jun 26
Cauliflower (semi-hardy)[12] Apr 17 not listed
Parsnips (semi-hardy)[12] Apr 17 Jun 26
Potatoes (semi-hardy)[12] Apr 17 Aug 20
Swiss chard (semi-hardy)[12] Apr 17 Jun 16
Snap beans (tender)[12] May 1 Jun 30
Sweet corn (tender)[12] May 1 Jun 30
Cucumbers (tender)[12] May 1 Jun 25
Summer squash (tender)[12] May 1 Jun 20
Cantaloupe (very tender)[12] May 15 Aug 8
Eggplant (very tender)[12] May 15 Jul 14 (from transplants)
Peppers (very tender)[12] May 15 Jul 24 (from transplants)
Tomatoes (very tender)[12] May 15 Jul 19 (from transplants)
Winter squash (very tender)[12] May 15 Aug 23
Watermelon (very tender)[12] May 15 Aug 8
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 coldest night of the winter averaged -15°F to -10°F over 1991 to 2020[1]. The zone is about winter cold, not frost dates or summer heat[14]. Madison spans more than one zone. By land area, 82% of the city lies in ZIP code areas rated zone 5b and 18% in areas rated zone 5a[15].

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

Share of the city's land area by ZIP code zone: zone 5b 82%, zone 5a 18%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
53704[15] 5b -15 to -10°F
53718[15] 5b -15 to -10°F
53711[15] 5b -15 to -10°F
53719[15] 5b -15 to -10°F
53705[15] 5b -15 to -10°F
53713[15] 5a -20 to -15°F
53593[15] 5a -20 to -15°F
53714[15] 5b -15 to -10°F
53716[15] 5b -15 to -10°F
53717[15] 5b -15 to -10°F
53703[15] 5b -15 to -10°F
53562[15] 5a -20 to -15°F
53715[15] 5a -20 to -15°F
53726[15] 5b -15 to -10°F
53558[15] 5b -15 to -10°F
53597[15] 5a -20 to -15°F
53706[15] 5a -20 to -15°F
53590[15] 5a -20 to -15°F
53532[15] 5a -20 to -15°F
53792[15] 5a -20 to -15°F

Questions people ask

What growing zone is Madison, Wisconsin?
The 2023 USDA map puts the center of Madison in zone 5b[1]. About 18% of the city's land area lies in ZIP code areas rated zone 5a[15].
When is the last frost in Madison?
At the Uw Arboretum - Madison station, the median last spring frost is May 1[2]. In 1 of 10 years the last frost comes after May 17[2].
When to plant tomatoes in Madison?
Using Colorado State University Extension's rule of typically 2 or more weeks after the average last frost, the earliest start for tomatoes is May 15[11].
When is the first frost in Madison?
The median first fall frost is October 9[3]. In 1 of 10 years it comes before September 26[3].
How long is the growing season in Madison?
In half of years the growing season between the last spring and first fall frost is at least 161 days[4]. In 9 of 10 years it is at least 140 days[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Madison, Wisconsin 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 15°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 18, in half of years after May 1, and in 1 of 10 years after May 17 (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 26, in half of years before October 9, and in 9 of 10 years before October 24 (NOAA 1991 to 2020 normals). The median first frost date is October 9. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 140 days in 9 of 10 years, at least 161 days in half of years, and at least 179 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Uw Arboretum - Madison weather station (USC00470273), 3.2 miles from the center of Madison at 870 feet, using 27 years of records from 1991 to 2020. NOAA Climate Normals 1991-2020
  6. Hard freeze (28°F) at this station: the median last spring date is April 20 and the median first fall date is October 20. 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. 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. Madison, Wisconsin overlaps 20 ZIP code areas. By land area, 82% lies in ZIP code areas rated zone 5b, 18% lies in ZIP code areas rated zone 5a. 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.