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Frost dates and planting calendar for Charleston, South Carolina

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
Feb 4[2]
Median first fall frost
Dec 30[3]
Growing season, median
321 days[4]

Charleston, South Carolina sits in USDA hardiness zone 9a[1]. In half of years the last spring frost comes after February 4, so that is the median last frost date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Jan 5, half of years Feb 4, 1 in 10 years after Mar 4Last frostmedian Feb 4First frostmedian Dec 30Frost riskHardyHardy vegetables: plant Jan 7 to Jan 21Jan 7 to Jan 21Semi-hardySemi-hardy vegetables: plant Jan 21 to Feb 4Jan 21 to Feb 4TenderTender vegetables: plant around Feb 4around Feb 4Very tenderVery tender vegetables: plant from Feb 18from Feb 18
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 Charleston City weather station, using records from 1991 to 2020[5]. They are chances, not promises. In half of years the last spring frost comes after February 4, and in 1 of 10 years it comes after March 4[2]. In the fall, the first frost comes before December 2 in 1 of 10 years and before December 30 in half of years[3].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after January 5 after February 4 after March 4
First fall frost (32°F)[3] before December 2 before December 30 before January 25
  • Hard freeze (28°F): median last spring date January 24, median first fall date January 8[7].
  • Frost-free growing season: at least 289 days in 9 of 10 years, 321 days in half of years and 357 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 92.3% of years and 28°F or colder in 63.4% of years[8].
  • Weather station: Charleston City (USW00013782), 4.1 miles from the city center, 10 feet, 30 years of 1991 to 2020 records[5].

When to plant vegetables

The planting rules come from Colorado State University Extension's vegetable guide, which was written for Colorado[6]. GardenFacts applies those rules to the NOAA median last frost of February 4[6]. Hardy vegetables like lettuce, peas and spinach can go in as early as January 7 to January 21[6]. Semi-hardy vegetables like beets, carrots and potatoes can go in as early as January 21, up to February 4[9]. Tender vegetables like snap beans and sweet corn go in from seed around February 4[10], and very tender ones like tomatoes and peppers typically wait 2 or more weeks after the median last frost, with February 18 as 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 (February 4) is January 7 to January 21[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (February 4) is January 21, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, February 4[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (February 4), is February 18[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Jan 7 Mar 13 (from transplants)
Cabbage (hardy)[12] Jan 7 Apr 2 (from transplants)
Kohlrabi (hardy)[12] Jan 7 Feb 26
Lettuce (hardy)[12] Jan 7 Mar 8
Onions (hardy)[12] Jan 7 Apr 27
Peas (hardy)[12] Jan 7 Mar 13
Radishes (hardy)[12] Jan 7 Feb 6
Spinach (hardy)[12] Jan 7 Feb 16
Turnips (hardy)[12] Jan 7 Feb 26
Beets (semi-hardy)[12] Jan 21 Mar 22
Carrots (semi-hardy)[12] Jan 21 Apr 1
Cauliflower (semi-hardy)[12] Jan 21 not listed
Parsnips (semi-hardy)[12] Jan 21 Apr 1
Potatoes (semi-hardy)[12] Jan 21 May 26
Swiss chard (semi-hardy)[12] Jan 21 Mar 22
Snap beans (tender)[12] Feb 4 Apr 5
Sweet corn (tender)[12] Feb 4 Apr 5
Cucumbers (tender)[12] Feb 4 Mar 31
Summer squash (tender)[12] Feb 4 Mar 26
Cantaloupe (very tender)[12] Feb 18 May 14
Eggplant (very tender)[12] Feb 18 Apr 19 (from transplants)
Peppers (very tender)[12] Feb 18 Apr 29 (from transplants)
Tomatoes (very tender)[12] Feb 18 Apr 24 (from transplants)
Winter squash (very tender)[12] Feb 18 May 29
Watermelon (very tender)[12] Feb 18 May 14
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 winter averages 20°F to 25°F, based on 1991 to 2020[1]. The zone is about winter cold, not summer heat or frost dates[14]. USDA describes the map as the standard gardeners use to judge which perennial plants are likely to thrive in a place[14]. All of Charleston's land area lies 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
29492[15] 9a 20 to 25°F
29414[15] 9a 20 to 25°F
29412[15] 9a 20 to 25°F
29455[15] 9a 20 to 25°F
29407[15] 9a 20 to 25°F
29403[15] 9a 20 to 25°F
29401[15] 9a 20 to 25°F
29405[15] 9a 20 to 25°F

Questions people ask

What growing zone is Charleston, South Carolina?
The 2023 USDA Plant Hardiness Zone Map puts Charleston in zone 9a[1]. By land area, 100% of the city lies in ZIP code areas rated zone 9a[15].
When is the last frost in Charleston?
The median last spring frost at the Charleston City station is February 4[2]. In 1 of 10 years the last frost comes after March 4[2].
When is the first frost in Charleston?
The median first fall frost is December 30[3]. In 1 of 10 years the first frost comes before December 2[3].
When to plant tomatoes in Charleston?
CSU Extension's rule is typically 2 or more weeks after the average last spring frost[11]. For Charleston the earliest start by that rule is February 18[11].
How long is the growing season in Charleston?
In half of years the growing season between the last spring frost and first fall frost is at least 321 days[4]. In 9 of 10 years it is at least 289 days[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Charleston, South Carolina 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 January 5, in half of years after February 4, and in 1 of 10 years after March 4 (NOAA 1991 to 2020 normals). The median last frost date is February 4. NOAA Climate Normals 1991-2020
  3. First fall frost (32°F) at this station: in 1 of 10 years the first frost comes before December 2, in half of years before December 30, and in 9 of 10 years before January 25 (NOAA 1991 to 2020 normals). The median first frost date is December 30. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 289 days in 9 of 10 years, at least 321 days in half of years, and at least 357 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Charleston City weather station (USW00013782), 4.1 miles from the center of Charleston at 10 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 January 24 and the median first fall date is January 8. NOAA Climate Normals 1991-2020
  8. At this station the low reached 32°F or colder in 92.3% of years from 1991 to 2020, and 28°F or colder in 63.4% 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. Charleston, South Carolina overlaps 8 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.