GardenFacts

All states › Missouri › St. Louis

Frost dates and planting calendar for St. Louis, Missouri

Updated October 30, 2026. Based on USDA, NOAA and Colorado State University Extension data. Published by Humblebee.

USDA hardiness zone
7a[1]
Median last spring frost
Apr 1[2]
Median first fall frost
Nov 4[3]
Growing season, median
218 days[4]

St. Louis, Missouri sits in USDA hardiness zone 7a at the city center[1]. The median last spring frost at the nearby NOAA station is April 1, so in half of years the last frost comes after that date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Mar 14, half of years Apr 1, 1 in 10 years after Apr 18Last frostmedian Apr 1First fall frost: 9 in 10 years before Nov 21, half of years Nov 4, 1 in 10 years before Oct 24First frostmedian Nov 4Frost riskHardyHardy vegetables: plant Mar 4 to Mar 18Mar 4 to Mar 18Semi-hardySemi-hardy vegetables: plant Mar 18 to Apr 1Mar 18 to Apr 1TenderTender vegetables: plant around Apr 1around Apr 1Very tenderVery tender vegetables: plant from Apr 15from Apr 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 come from NOAA climate normals for the St Louis Sci Ctr weather station, using records from 1991 to 2020[5]. In 9 of 10 years the last spring frost comes after March 14, and in 1 of 10 years it comes after April 18[2]. In the fall, the first frost comes before October 24 in 1 of 10 years, and before November 21 in 9 of 10 years[3]. The median first fall frost is November 4[3]. These are odds from past weather, 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 March 14 after April 1 after April 18
First fall frost (32°F)[3] before October 24 before November 4 before November 21
  • Hard freeze (28°F): median last spring date March 22, median first fall date November 15[7].
  • Frost-free growing season: at least 198 days in 9 of 10 years, 218 days in half of years and 240 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: St Louis Sci Ctr (USC00237452), 1.5 miles from the city center, 515 feet, 25 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, so GardenFacts applies its rules to St. Louis dates as a simple calculation[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 4 to March 18[6]. Semi-hardy vegetables such as carrots, potatoes and beets can go in as early as 2 weeks before the median last frost, March 18, up to the median date itself[9]. Tender vegetables such as snap beans and sweet corn can be seeded around the median last frost date, April 1[10]. Very tender vegetables such as tomatoes and peppers typically start 2 or more weeks after the median last frost, and the earliest start is April 15[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 1) is March 4 to March 18[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 1) is March 18, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 1[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 1), is April 15[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 4 May 8 (from transplants)
Cabbage (hardy)[12] Mar 4 May 28 (from transplants)
Kohlrabi (hardy)[12] Mar 4 Apr 23
Lettuce (hardy)[12] Mar 4 May 3
Onions (hardy)[12] Mar 4 Jun 22
Peas (hardy)[12] Mar 4 May 8
Radishes (hardy)[12] Mar 4 Apr 3
Spinach (hardy)[12] Mar 4 Apr 13
Turnips (hardy)[12] Mar 4 Apr 23
Beets (semi-hardy)[12] Mar 18 May 17
Carrots (semi-hardy)[12] Mar 18 May 27
Cauliflower (semi-hardy)[12] Mar 18 not listed
Parsnips (semi-hardy)[12] Mar 18 May 27
Potatoes (semi-hardy)[12] Mar 18 Jul 21
Swiss chard (semi-hardy)[12] Mar 18 May 17
Snap beans (tender)[12] Apr 1 May 31
Sweet corn (tender)[12] Apr 1 May 31
Cucumbers (tender)[12] Apr 1 May 26
Summer squash (tender)[12] Apr 1 May 21
Cantaloupe (very tender)[12] Apr 15 Jul 9
Eggplant (very tender)[12] Apr 15 Jun 14 (from transplants)
Peppers (very tender)[12] Apr 15 Jun 24 (from transplants)
Tomatoes (very tender)[12] Apr 15 Jun 19 (from transplants)
Winter squash (very tender)[12] Apr 15 Jul 24
Watermelon (very tender)[12] Apr 15 Jul 9
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 7a means the coldest night of the winter averages 0°F to 5°F over 1991 to 2020[1]. The zone is based on that winter minimum, not on summer heat or frost dates[14]. All of the city's land area lies in ZIP code areas rated zone 7a[15].

Zone 7a: average annual extreme minimum temperature 0°F to 5°F (1991 to 2020)[1]. Modeled value at the city center: 1.4°F[1].

Share of the city's land area by ZIP code zone: zone 7a 100%[15].

All towns in zone 7a and what zone 7a means

Zone by ZIP code
ZIP code Zone Coldest night range
63110[15] 7a 0 to 5°F
63147[15] 7a 0 to 5°F
63116[15] 7a 0 to 5°F
63115[15] 7a 0 to 5°F
63139[15] 7a 0 to 5°F
63109[15] 7a 0 to 5°F
63118[15] 7a 0 to 5°F
63104[15] 7a 0 to 5°F
63111[15] 7a 0 to 5°F
63112[15] 7a 0 to 5°F
63113[15] 7a 0 to 5°F
63107[15] 7a 0 to 5°F
63108[15] 7a 0 to 5°F
63120[15] 7a 0 to 5°F
63106[15] 7a 0 to 5°F
63103[15] 7a 0 to 5°F
63102[15] 7a 0 to 5°F
63137[15] 7a 0 to 5°F
63123[15] 7a 0 to 5°F
63143[15] 7a 0 to 5°F
63136[15] 7a 0 to 5°F
63101[15] 7a 0 to 5°F
63138[15] 7a 0 to 5°F
63125[15] 7a 0 to 5°F
63117[15] 7a 0 to 5°F
63105[15] 7a 0 to 5°F
63130[15] 7a 0 to 5°F
63119[15] 7a 0 to 5°F
63133[15] 7a 0 to 5°F
63155[15] 7a 0 to 5°F

Questions people ask

What growing zone is St. Louis, Missouri?
The 2023 USDA Plant Hardiness Zone Map puts the center of St. Louis in zone 7a[1]. By land area, 100% of the city lies in ZIP code areas rated zone 7a[15].
When is the last frost in St. Louis?
The median last spring frost is April 1, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after April 18[2].
When to plant tomatoes in St. Louis?
Colorado State University Extension says very tender vegetables like tomatoes typically start 2 or more weeks after the average last spring frost[11]. Using the NOAA median last frost, the earliest start is April 15[11].
When is the first frost in St. Louis?
The median first fall frost is November 4, so in half of years the first frost comes before that date[3]. In 1 of 10 years it comes before October 24[3].
How long is the growing season in St. Louis?
The growing season is at least 218 days in half of years[4]. It is at least 198 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of St. Louis, Missouri in zone 7a. Zone 7a means an average annual extreme minimum temperature of 0°F to 5°F over 1991 to 2020. The map's modeled value at the city center is 1.4°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 March 14, in half of years after April 1, and in 1 of 10 years after April 18 (NOAA 1991 to 2020 normals). The median last frost date is April 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 October 24, in half of years before November 4, and in 9 of 10 years before November 21 (NOAA 1991 to 2020 normals). The median first frost date is November 4. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 198 days in 9 of 10 years, at least 218 days in half of years, and at least 240 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the St Louis Sci Ctr weather station (USC00237452), 1.5 miles from the center of St. Louis at 515 feet, using 25 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 March 22 and the median first fall date is November 15. 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. St. Louis, Missouri overlaps 30 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 7a. 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.