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Frost dates and planting calendar for Mobile, Alabama

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

USDA hardiness zone
9a[1]
Median last spring frost
Mar 3[2]
Median first fall frost
Nov 25[3]
Growing season, median
268 days[4]

The center of Mobile, Alabama is in USDA hardiness zone 9a[1]. The median last spring frost at the Mobile weather station is March 3[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Feb 6, half of years Mar 3, 1 in 10 years after Mar 21Last frostmedian Mar 3First fall frost: 9 in 10 years before Dec 22, half of years Nov 25, 1 in 10 years before Nov 8First frostmedian Nov 25Frost riskHardyHardy vegetables: plant Feb 3 to Feb 17Feb 3 to Feb 17Semi-hardySemi-hardy vegetables: plant Feb 17 to Mar 3Feb 17 to Mar 3TenderTender vegetables: plant around Mar 3around Mar 3Very tenderVery tender vegetables: plant from Mar 17from Mar 17
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 are odds from NOAA records for 1991 to 2020, not a forecast[5]. At the Mobile station, the last spring frost comes after March 3 in half of years[2]. In 1 of 10 years it comes after March 21[2]. The first fall frost comes before November 25 in half of years[3]. In 1 of 10 years it comes before November 8[3]. Any year can be earlier or later.

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after February 6 after March 3 after March 21
First fall frost (32°F)[3] before November 8 before November 25 before December 22
  • Hard freeze (28°F): median last spring date February 13, median first fall date December 14[7].
  • Frost-free growing season: at least 242 days in 9 of 10 years, 268 days in half of years and 300 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 100% of years and 28°F or colder in 98.7% of years[8].
  • Weather station: Mobile (USW00013894), 7.9 miles from the city center, 208 feet, 30 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, so these dates are a starting point[6]. Hardy vegetables such as broccoli, lettuce and spinach can go in as early as 2 to 4 weeks before the median last frost, which is February 3 to February 17[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 February 17[9]. Tender vegetables such as snap beans and sweet corn can start from seed around March 3[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 March 17[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (March 3) is February 3 to February 17[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (March 3) is February 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 3[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (March 3), is March 17[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Feb 3 Apr 9 (from transplants)
Cabbage (hardy)[12] Feb 3 Apr 29 (from transplants)
Kohlrabi (hardy)[12] Feb 3 Mar 25
Lettuce (hardy)[12] Feb 3 Apr 4
Onions (hardy)[12] Feb 3 May 24
Peas (hardy)[12] Feb 3 Apr 9
Radishes (hardy)[12] Feb 3 Mar 5
Spinach (hardy)[12] Feb 3 Mar 15
Turnips (hardy)[12] Feb 3 Mar 25
Beets (semi-hardy)[12] Feb 17 Apr 18
Carrots (semi-hardy)[12] Feb 17 Apr 28
Cauliflower (semi-hardy)[12] Feb 17 not listed
Parsnips (semi-hardy)[12] Feb 17 Apr 28
Potatoes (semi-hardy)[12] Feb 17 Jun 22
Swiss chard (semi-hardy)[12] Feb 17 Apr 18
Snap beans (tender)[12] Mar 3 May 2
Sweet corn (tender)[12] Mar 3 May 2
Cucumbers (tender)[12] Mar 3 Apr 27
Summer squash (tender)[12] Mar 3 Apr 22
Cantaloupe (very tender)[12] Mar 17 Jun 10
Eggplant (very tender)[12] Mar 17 May 16 (from transplants)
Peppers (very tender)[12] Mar 17 May 26 (from transplants)
Tomatoes (very tender)[12] Mar 17 May 21 (from transplants)
Winter squash (very tender)[12] Mar 17 Jun 25
Watermelon (very tender)[12] Mar 17 Jun 10
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 9a means the coldest night of the year averages 20°F to 25°F, based on 1991 to 2020[1]. The zone is about winter lows, not summer heat or frost dates[14]. All of Mobile by land area is in ZIP code areas rated zone 9a[15].

Zone 9a: average annual extreme minimum temperature 20°F to 25°F (1991 to 2020)[1]. Modeled value at the city center: 22.5°F[1].

Share of the city's land area by ZIP code zone: zone 9a 100%[15].

All towns in zone 9a and what zone 9a means

Zone by ZIP code
ZIP code Zone Coldest night range
36608[15] 9a 20 to 25°F
36605[15] 9a 20 to 25°F
36693[15] 9a 20 to 25°F
36618[15] 9a 20 to 25°F
36582[15] 9a 20 to 25°F
36619[15] 9a 20 to 25°F
36606[15] 9a 20 to 25°F
36609[15] 9a 20 to 25°F
36695[15] 9a 20 to 25°F
36617[15] 9a 20 to 25°F
36602[15] 9a 20 to 25°F
36603[15] 9a 20 to 25°F
36615[15] 9a 20 to 25°F
36610[15] 9a 20 to 25°F
36607[15] 9a 20 to 25°F
36604[15] 9a 20 to 25°F
36571[15] 9a 20 to 25°F
36688[15] 9a 20 to 25°F
36575[15] 9a 20 to 25°F
36611[15] 9a 20 to 25°F
36613[15] 9a 20 to 25°F
36612[15] 9a 20 to 25°F
36652[15] 9a 20 to 25°F

Questions people ask

What growing zone is Mobile, Alabama?
The center of Mobile is in USDA zone 9a[1]. By land area, 100% of the city is in ZIP code areas rated 9a[15].
When is the last frost in Mobile?
The median last spring frost is March 3[2]. In 1 of 10 years the last frost comes after March 21[2].
When to plant tomatoes in Mobile?
CSU Extension says tomatoes typically go in 2 or more weeks after the average last frost[11]. Using the median last frost, the earliest start is March 17[11].
When is the first frost in Mobile?
The median first fall frost is November 25[3]. In 1 of 10 years it comes before November 8[3].
How long is the growing season in Mobile?
The growing season is at least 268 days in half of years[4]. It is at least 242 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Mobile, Alabama in zone 9a. Zone 9a means an average annual extreme minimum temperature of 20°F to 25°F over 1991 to 2020. The map's modeled value at the city center is 22.5°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 February 6, in half of years after March 3, and in 1 of 10 years after March 21 (NOAA 1991 to 2020 normals). The median last frost date is March 3. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before November 8, in half of years before November 25, and in 9 of 10 years before December 22 (NOAA 1991 to 2020 normals). The median first frost date is November 25. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 242 days in 9 of 10 years, at least 268 days in half of years, and at least 300 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Mobile weather station (USW00013894), 7.9 miles from the center of Mobile at 208 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 February 13 and the median first fall date is December 14. 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 98.7% 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. Mobile, Alabama overlaps 23 ZIP code areas. By land area, 100% lies in ZIP code areas rated zone 9a. 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.