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Frost dates and planting calendar for Peoria, 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 16[2]
Median first fall frost
Oct 23[3]
Growing season, median
189 days[4]

Peoria, Illinois is in USDA hardiness zone 6a on the 2023 map[1]. The median last spring frost at the nearby NOAA station is April 16[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Apr 2, half of years Apr 16, 1 in 10 years after May 4Last frostmedian Apr 16First fall frost: 9 in 10 years before Nov 3, half of years Oct 23, 1 in 10 years before Oct 9First frostmedian Oct 23Frost riskHardyHardy vegetables: plant Mar 19 to Apr 2Mar 19 to Apr 2Semi-hardySemi-hardy vegetables: plant Apr 2 to Apr 16Apr 2 to Apr 16TenderTender vegetables: plant around Apr 16around Apr 16Very tenderVery tender vegetables: plant from Apr 30from Apr 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.

NOAA records from 1991 to 2020 give the odds, not a forecast. The median last spring frost is April 16, so in half of years the last frost comes after that date[2]. In 1 of 10 years the last frost comes after May 4[2]. In half of years the first fall frost comes before October 23, and in 1 of 10 years it comes before October 9[3]. These dates come from the Peoria Gtr Peoria Airport station[5].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after April 2 after April 16 after May 4
First fall frost (32°F)[3] before October 9 before October 23 before November 3
  • Hard freeze (28°F): median last spring date April 5, median first fall date November 2[7].
  • Frost-free growing season: at least 167 days in 9 of 10 years, 189 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: Peoria Gtr Peoria Airport (USW00014842), 6.8 miles from the city center, 650 feet, 30 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its planting guide for Colorado, so these dates are simple arithmetic and not local advice[6]. Hardy vegetables such as lettuce, peas and spinach can go in as early as 2 to 4 weeks before the median last frost, which is March 19 to April 2[6]. Semi-hardy vegetables such as carrots and potatoes can go in as early as 2 weeks before it, from April 2 up to the median date[9]. Tender vegetables such as snap beans and sweet corn can start from seed around April 16[10]. Very tender vegetables such as tomatoes and peppers typically wait 2 or more weeks after the median last frost, so the earliest start is April 30[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 16) is March 19 to April 2[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 16) is April 2, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 16[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 16), is April 30[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 19 May 23 (from transplants)
Cabbage (hardy)[12] Mar 19 Jun 12 (from transplants)
Kohlrabi (hardy)[12] Mar 19 May 8
Lettuce (hardy)[12] Mar 19 May 18
Onions (hardy)[12] Mar 19 Jul 7
Peas (hardy)[12] Mar 19 May 23
Radishes (hardy)[12] Mar 19 Apr 18
Spinach (hardy)[12] Mar 19 Apr 28
Turnips (hardy)[12] Mar 19 May 8
Beets (semi-hardy)[12] Apr 2 Jun 1
Carrots (semi-hardy)[12] Apr 2 Jun 11
Cauliflower (semi-hardy)[12] Apr 2 not listed
Parsnips (semi-hardy)[12] Apr 2 Jun 11
Potatoes (semi-hardy)[12] Apr 2 Aug 5
Swiss chard (semi-hardy)[12] Apr 2 Jun 1
Snap beans (tender)[12] Apr 16 Jun 15
Sweet corn (tender)[12] Apr 16 Jun 15
Cucumbers (tender)[12] Apr 16 Jun 10
Summer squash (tender)[12] Apr 16 Jun 5
Cantaloupe (very tender)[12] Apr 30 Jul 24
Eggplant (very tender)[12] Apr 30 Jun 29 (from transplants)
Peppers (very tender)[12] Apr 30 Jul 9 (from transplants)
Tomatoes (very tender)[12] Apr 30 Jul 4 (from transplants)
Winter squash (very tender)[12] Apr 30 Aug 8
Watermelon (very tender)[12] Apr 30 Jul 24
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

A zone shows the average coldest winter night from 1991 to 2020 and does not show frost dates or summer heat[14]. Zone 6a means -10°F to -5°F[1]. Peoria is mostly zone 6a, with 95% of its land area in 6a ZIP code areas and 5% in zone 5b ones[15].

Zone 6a: average annual extreme minimum temperature -10°F to -5°F (1991 to 2020)[1]. Modeled value at the city center: -9.7°F[1].

Share of the city's land area by ZIP code zone: zone 6a 95%, zone 5b 5%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
61615[15] 6a -10 to -5°F
61614[15] 6a -10 to -5°F
61604[15] 6a -10 to -5°F
61603[15] 6a -10 to -5°F
61605[15] 6a -10 to -5°F
61525[15] 5b -15 to -10°F
61606[15] 6a -10 to -5°F
61602[15] 6a -10 to -5°F
61607[15] 6a -10 to -5°F
61528[15] 5b -15 to -10°F
61616[15] 6a -10 to -5°F

Questions people ask

What growing zone is Peoria, Illinois?
The center of Peoria is in USDA zone 6a on the 2023 map[1]. By land area, 95% is in zone 6a ZIP code areas and 5% is in zone 5b[15].
When is the last frost in Peoria?
The median last spring frost is April 16, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after May 4[2].
When to plant tomatoes in Peoria?
CSU Extension says tomatoes are very tender and typically go in 2 or more weeks after the average last frost[11]. Using the median last frost, the earliest start is April 30[11].
When is the first frost in Peoria?
The median first fall frost is October 23[3]. In 1 of 10 years it comes before October 9[3].
How long is the growing season in Peoria?
The growing season is at least 189 days in half of years[4]. It is at least 167 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Peoria, 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 9.7°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 2, in half of years after April 16, and in 1 of 10 years after May 4 (NOAA 1991 to 2020 normals). The median last frost date is April 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 October 9, in half of years before October 23, and in 9 of 10 years before November 3 (NOAA 1991 to 2020 normals). The median first frost date is October 23. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 167 days in 9 of 10 years, at least 189 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 Peoria Gtr Peoria Airport weather station (USW00014842), 6.8 miles from the center of Peoria at 650 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 5 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. Peoria, Illinois overlaps 11 ZIP code areas. By land area, 95% lies in ZIP code areas rated zone 6a, 5% lies in ZIP code areas rated zone 5b. 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.