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Frost dates and planting calendar for Champaign, Illinois

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
Apr 15[2]
Median first fall frost
Oct 24[3]
Growing season, median
190 days[4]

Champaign, Illinois is in USDA hardiness zone 6a[1]. The median last spring frost is April 15, which means that in half of years the last frost comes after that date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 1, half of years Apr 15, 1 in 10 years after Apr 29Last frostmedian Apr 15First fall frost: 9 in 10 years before Nov 5, half of years Oct 24, 1 in 10 years before Oct 11First frostmedian Oct 24Frost riskHardyHardy vegetables: plant Mar 18 to Apr 1Mar 18 to Apr 1Semi-hardySemi-hardy vegetables: plant Apr 1 to Apr 15Apr 1 to Apr 15TenderTender vegetables: plant around Apr 15around Apr 15Very tenderVery tender vegetables: plant from Apr 29from Apr 29
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.

The frost dates here come from NOAA climate normals for the Champaign 3S weather station, using records from 1991 to 2020[5]. In 9 of 10 years the last spring frost comes after April 1, and in 1 of 10 years it comes after April 29[2]. In half of years the first fall frost comes before October 24, and in 1 of 10 years it comes before October 11[3]. These are odds from past years and not a forecast, so any year can be earlier or later[5].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 1 after April 15 after April 29
First fall frost (32°F)[3] before October 11 before October 24 before November 5
  • Hard freeze (28°F): median last spring date April 4, median first fall date November 2[7].
  • Frost-free growing season: at least 171 days in 9 of 10 years, 190 days in half of years and 209 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: Champaign 3S (USC00118740), 2.8 miles from the city center, 721 feet, 29 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, so treat these dates as a starting point[6]. Hardy vegetables such as broccoli, lettuce, peas and spinach can go in as early as 2 to 4 weeks before the median last frost, which works out to March 18 to April 1[6]. Semi-hardy vegetables such as beets, carrots and potatoes can go in as early as 2 weeks before the median last frost, which is April 1[9]. Tender vegetables such as snap beans, sweet corn and cucumbers go in from seed around the median last frost date, April 15[10]. Very tender vegetables such as tomatoes, peppers and eggplant typically go in 2 or more weeks after it, and April 29 is the earliest start[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 15) is March 18 to April 1[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 15) is April 1, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 15[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 15), is April 29[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 18 May 22 (from transplants)
Cabbage (hardy)[12] Mar 18 Jun 11 (from transplants)
Kohlrabi (hardy)[12] Mar 18 May 7
Lettuce (hardy)[12] Mar 18 May 17
Onions (hardy)[12] Mar 18 Jul 6
Peas (hardy)[12] Mar 18 May 22
Radishes (hardy)[12] Mar 18 Apr 17
Spinach (hardy)[12] Mar 18 Apr 27
Turnips (hardy)[12] Mar 18 May 7
Beets (semi-hardy)[12] Apr 1 May 31
Carrots (semi-hardy)[12] Apr 1 Jun 10
Cauliflower (semi-hardy)[12] Apr 1 not listed
Parsnips (semi-hardy)[12] Apr 1 Jun 10
Potatoes (semi-hardy)[12] Apr 1 Aug 4
Swiss chard (semi-hardy)[12] Apr 1 May 31
Snap beans (tender)[12] Apr 15 Jun 14
Sweet corn (tender)[12] Apr 15 Jun 14
Cucumbers (tender)[12] Apr 15 Jun 9
Summer squash (tender)[12] Apr 15 Jun 4
Cantaloupe (very tender)[12] Apr 29 Jul 23
Eggplant (very tender)[12] Apr 29 Jun 28 (from transplants)
Peppers (very tender)[12] Apr 29 Jul 8 (from transplants)
Tomatoes (very tender)[12] Apr 29 Jul 3 (from transplants)
Winter squash (very tender)[12] Apr 29 Aug 7
Watermelon (very tender)[12] Apr 29 Jul 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 2023 USDA map puts the center of Champaign in zone 6a, which means an average coldest night of -10°F to -5°F over 1991 to 2020[1]. The zone is based on the coldest winter night and not on frost dates or summer heat[14]. All of the city's land area lies in ZIP code areas rated zone 6a, so the city does not span more than one zone[15].

Zone 6a: average annual extreme minimum temperature -10°F to -5°F (1991 to 2020)[1]. Modeled value at the city center: -8.5°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
61822[15] 6a -10 to -5°F
61821[15] 6a -10 to -5°F
61820[15] 6a -10 to -5°F
61802[15] 6a -10 to -5°F
61801[15] 6a -10 to -5°F

Questions people ask

What growing zone is Champaign, Illinois?
The 2023 USDA Plant Hardiness Zone Map puts the center of Champaign in zone 6a[1]. All of the city's land area is in ZIP code areas rated zone 6a[15].
When is the last frost in Champaign?
The median last spring frost is April 15, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after April 29[2].
When is the first frost in Champaign?
The median first fall frost is October 24, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before October 11[3].
When to plant tomatoes in Champaign?
CSU Extension groups tomatoes as very tender and typically plants them 2 or more weeks after the average last frost, and for Champaign the earliest start works out to April 29[11]. CSU's guide was written for Colorado[11].
How long is the growing season in Champaign?
The growing season is at least 190 days in half of years[4]. It is at least 171 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Champaign, Illinois 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 8.5°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 1, in half of years after April 15, and in 1 of 10 years after April 29 (NOAA 1991 to 2020 normals). The median last frost date is April 15. 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 11, in half of years before October 24, and in 9 of 10 years before November 5 (NOAA 1991 to 2020 normals). The median first frost date is October 24. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 171 days in 9 of 10 years, at least 190 days in half of years, and at least 209 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Champaign 3S weather station (USC00118740), 2.8 miles from the center of Champaign at 721 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 4 and the median first fall date is November 2. 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. Champaign, Illinois overlaps 5 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.