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Frost dates and planting calendar for Tulsa, Oklahoma

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

USDA hardiness zone
7b[1]
Median last spring frost
Mar 31[2]
Median first fall frost
Nov 4[3]
Growing season, median
220 days[4]

Tulsa is in USDA hardiness zone 7b on the 2023 map[1]. The median last spring frost is March 31, 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 Mar 11, half of years Mar 31, 1 in 10 years after Apr 15Last frostmedian Mar 31First fall frost: 9 in 10 years before Nov 19, half of years Nov 4, 1 in 10 years before Oct 20First frostmedian Nov 4Frost riskHardyHardy vegetables: plant Mar 3 to Mar 17Mar 3 to Mar 17Semi-hardySemi-hardy vegetables: plant Mar 17 to Mar 31Mar 17 to Mar 31TenderTender vegetables: plant around Mar 31around Mar 31Very tenderVery tender vegetables: plant from Apr 14from Apr 14
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 Tulsa International Airport station, using records from 1991 to 2020[5]. In half of years the last spring frost comes after March 31, and in 1 of 10 years it comes after April 15[2]. In the fall, the first frost comes before November 4 in half of years, and before October 20 in 1 of 10 years[3]. These are odds from past records 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 March 11 after March 31 after April 15
First fall frost (32°F)[3] before October 20 before November 4 before November 19
  • Hard freeze (28°F): median last spring date March 17, median first fall date November 13[7].
  • Frost-free growing season: at least 198 days in 9 of 10 years, 220 days in half of years and 243 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: Tulsa International Airport (USW00013968), 5 miles from the city center, 650 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 Tulsa dates are a simple calculation from its rules[6]. Hardy vegetables such as broccoli, lettuce and peas can go in as early as 2 to 4 weeks before the median last frost, which is March 3 to March 17[6]. Semi-hardy vegetables such as carrots and potatoes can go in as early as 2 weeks before the median last frost, which is March 17[9]. Tender vegetables such as snap beans and sweet corn can be started from seed around March 31[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 14[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (March 31) is March 3 to March 17[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (March 31) is March 17, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, March 31[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (March 31), is April 14[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 3 May 7 (from transplants)
Cabbage (hardy)[12] Mar 3 May 27 (from transplants)
Kohlrabi (hardy)[12] Mar 3 Apr 22
Lettuce (hardy)[12] Mar 3 May 2
Onions (hardy)[12] Mar 3 Jun 21
Peas (hardy)[12] Mar 3 May 7
Radishes (hardy)[12] Mar 3 Apr 2
Spinach (hardy)[12] Mar 3 Apr 12
Turnips (hardy)[12] Mar 3 Apr 22
Beets (semi-hardy)[12] Mar 17 May 16
Carrots (semi-hardy)[12] Mar 17 May 26
Cauliflower (semi-hardy)[12] Mar 17 not listed
Parsnips (semi-hardy)[12] Mar 17 May 26
Potatoes (semi-hardy)[12] Mar 17 Jul 20
Swiss chard (semi-hardy)[12] Mar 17 May 16
Snap beans (tender)[12] Mar 31 May 30
Sweet corn (tender)[12] Mar 31 May 30
Cucumbers (tender)[12] Mar 31 May 25
Summer squash (tender)[12] Mar 31 May 20
Cantaloupe (very tender)[12] Apr 14 Jul 8
Eggplant (very tender)[12] Apr 14 Jun 13 (from transplants)
Peppers (very tender)[12] Apr 14 Jun 23 (from transplants)
Tomatoes (very tender)[12] Apr 14 Jun 18 (from transplants)
Winter squash (very tender)[12] Apr 14 Jul 23
Watermelon (very tender)[12] Apr 14 Jul 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 7b means the average coldest night of each winter falls between 5°F and 10°F, based on 1991 to 2020[1]. The zone is not about summer heat or frost dates[14]. USDA says the map helps gardeners judge which perennial plants are most likely to thrive[14]. All of Tulsa's land area lies in ZIP code areas rated zone 7b[15].

Zone 7b: average annual extreme minimum temperature 5°F to 10°F (1991 to 2020)[1]. Modeled value at the city center: 7.2°F[1].

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

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

Zone by ZIP code
ZIP code Zone Coldest night range
74115[15] 7b 5 to 10°F
74127[15] 7b 5 to 10°F
74116[15] 7b 5 to 10°F
74133[15] 7b 5 to 10°F
74134[15] 7b 5 to 10°F
74137[15] 7b 5 to 10°F
74015[15] 7b 5 to 10°F
74108[15] 7b 5 to 10°F
74132[15] 7b 5 to 10°F
74107[15] 7b 5 to 10°F
74136[15] 7b 5 to 10°F
74106[15] 7b 5 to 10°F
74105[15] 7b 5 to 10°F
74112[15] 7b 5 to 10°F
74135[15] 7b 5 to 10°F
74145[15] 7b 5 to 10°F
74110[15] 7b 5 to 10°F
74146[15] 7b 5 to 10°F
74114[15] 7b 5 to 10°F
74129[15] 7b 5 to 10°F
74117[15] 7b 5 to 10°F
74128[15] 7b 5 to 10°F
74104[15] 7b 5 to 10°F
74014[15] 7b 5 to 10°F
74126[15] 7b 5 to 10°F
74055[15] 7b 5 to 10°F
74120[15] 7b 5 to 10°F
74130[15] 7b 5 to 10°F
74008[15] 7b 5 to 10°F
74119[15] 7b 5 to 10°F

Questions people ask

What growing zone is Tulsa?
The 2023 USDA map puts the center of Tulsa in zone 7b[1]. All of the city's land area is in ZIP code areas rated 7b[15].
When is the last frost in Tulsa?
The median last spring frost is March 31, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after April 15[2].
When is the first frost in Tulsa?
The median first fall frost is November 4[3]. In 1 of 10 years the first frost comes before October 20[3].
When to plant tomatoes in Tulsa?
CSU Extension typically waits 2 or more weeks after the average last frost for tomatoes, which puts the earliest start at April 14[11]. CSU's guide was written for Colorado[11].
How long is the growing season in Tulsa?
The growing season is at least 220 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 Tulsa, Oklahoma in zone 7b. Zone 7b means an average annual extreme minimum temperature of 5°F to 10°F over 1991 to 2020. The map's modeled value at the city center is 7.2°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 11, in half of years after March 31, and in 1 of 10 years after April 15 (NOAA 1991 to 2020 normals). The median last frost date is March 31. 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 20, in half of years before November 4, and in 9 of 10 years before November 19 (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 220 days in half of years, and at least 243 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Tulsa International Airport weather station (USW00013968), 5 miles from the center of Tulsa at 650 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 March 17 and the median first fall date is November 13. 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. Tulsa, Oklahoma overlaps 36 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 7b. 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.