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Frost dates and planting calendar for Washington, District of Columbia

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

USDA hardiness zone
8a[1]
Median last spring frost
Mar 29[2]
Median first fall frost
Nov 8[3]
Growing season, median
224 days[4]

Washington sits in USDA hardiness zone 8a at the city center[1]. In half of years the last spring frost comes after March 29, the median date in NOAA records[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Mar 15, half of years Mar 29, 1 in 10 years after Apr 11Last frostmedian Mar 29First fall frost: 9 in 10 years before Nov 23, half of years Nov 8, 1 in 10 years before Oct 26First frostmedian Nov 8Frost riskHardyHardy vegetables: plant Mar 1 to Mar 15Mar 1 to Mar 15Semi-hardySemi-hardy vegetables: plant Mar 15 to Mar 29Mar 15 to Mar 29TenderTender vegetables: plant around Mar 29around Mar 29Very tenderVery tender vegetables: plant from Apr 12from Apr 12
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.

Frost dates here are odds, not promises. They come from NOAA climate normals for the Natl Arboretum Dc weather station, using records from 1991 to 2020[5]. In 1 of 10 years the last spring frost comes after April 11, and in 9 of 10 years it comes after March 15[2]. In the fall, the median first frost is November 8, and in 1 of 10 years the first frost comes before October 26[3]. In half of years the growing season lasts at least 224 days[4].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after March 15 after March 29 after April 11
First fall frost (32°F)[3] before October 26 before November 8 before November 23
  • Hard freeze (28°F): median last spring date March 17, median first fall date November 20[7].
  • Frost-free growing season: at least 205 days in 9 of 10 years, 224 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: Natl Arboretum Dc (USC00186350), 2.6 miles from the city center, 50 feet, 29 years of 1991 to 2020 records[5].

When to plant vegetables

The planting rules come from Colorado State University Extension, whose guide was written for Colorado[6]. GardenFacts applies those rules to the NOAA median last frost of March 29[6]. Hardy crops like lettuce, peas and spinach can go in as early as March 1 to March 15[6]. Semi-hardy crops like beets, carrots and potatoes can go in as early as March 15, up to the median date itself[9]. Snap beans, sweet corn, cucumbers and summer squash go in from seed around March 29[10], while tomatoes, peppers and other very tender crops typically wait 2 or more weeks after the median, with April 12 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 (March 29) is March 1 to March 15[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (March 29) is March 15, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, March 29[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (March 29), is April 12[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 1 May 5 (from transplants)
Cabbage (hardy)[12] Mar 1 May 25 (from transplants)
Kohlrabi (hardy)[12] Mar 1 Apr 20
Lettuce (hardy)[12] Mar 1 Apr 30
Onions (hardy)[12] Mar 1 Jun 19
Peas (hardy)[12] Mar 1 May 5
Radishes (hardy)[12] Mar 1 Mar 31
Spinach (hardy)[12] Mar 1 Apr 10
Turnips (hardy)[12] Mar 1 Apr 20
Beets (semi-hardy)[12] Mar 15 May 14
Carrots (semi-hardy)[12] Mar 15 May 24
Cauliflower (semi-hardy)[12] Mar 15 not listed
Parsnips (semi-hardy)[12] Mar 15 May 24
Potatoes (semi-hardy)[12] Mar 15 Jul 18
Swiss chard (semi-hardy)[12] Mar 15 May 14
Snap beans (tender)[12] Mar 29 May 28
Sweet corn (tender)[12] Mar 29 May 28
Cucumbers (tender)[12] Mar 29 May 23
Summer squash (tender)[12] Mar 29 May 18
Cantaloupe (very tender)[12] Apr 12 Jul 6
Eggplant (very tender)[12] Apr 12 Jun 11 (from transplants)
Peppers (very tender)[12] Apr 12 Jun 21 (from transplants)
Tomatoes (very tender)[12] Apr 12 Jun 16 (from transplants)
Winter squash (very tender)[12] Apr 12 Jul 21
Watermelon (very tender)[12] Apr 12 Jul 6
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 hardiness zone is based on the average coldest winter night, not on summer heat or frost dates[14]. Zone 8a means an average annual extreme minimum of 10°F to 15°F[1]. Washington spans more than one zone. By land area, 56% lies in ZIP code areas rated zone 7b and 43% in areas rated zone 8a[15].

Zone 8a: average annual extreme minimum temperature 10°F to 15°F (1991 to 2020)[1]. Modeled value at the city center: 10.9°F[1].

Share of the city's land area by ZIP code zone: zone 7b 56%, zone 8a 43%[15].

All towns in zone 8a and what zone 8a means

Zone by ZIP code
ZIP code Zone Coldest night range
20019[15] 8a 10 to 15°F
20011[15] 7b 5 to 10°F
20032[15] 8a 10 to 15°F
20002[15] 8a 10 to 15°F
20020[15] 7b 5 to 10°F
20016[15] 7b 5 to 10°F
20015[15] 7b 5 to 10°F
20007[15] 7b 5 to 10°F
20008[15] 7b 5 to 10°F
20018[15] 7b 5 to 10°F
20003[15] 8a 10 to 15°F
20017[15] 7b 5 to 10°F
20024[15] 8a 10 to 15°F
20012[15] 7b 5 to 10°F
20001[15] 8a 10 to 15°F
20009[15] 7b 5 to 10°F
20010[15] 7b 5 to 10°F
20037[15] 8a 10 to 15°F
20373[15] 8a 10 to 15°F
20005[15] 8a 10 to 15°F
20006[15] 8a 10 to 15°F
20317[15] 7b 5 to 10°F
20036[15] 8a 10 to 15°F
20064[15] 7b 5 to 10°F
20057[15] 7b 5 to 10°F
20565[15] 8a 10 to 15°F
20319[15] 8a 10 to 15°F
20422[15] 7b 5 to 10°F
20560[15] 8a 10 to 15°F
20230[15] 8a 10 to 15°F

Questions people ask

What growing zone is Washington, DC?
The 2023 USDA map puts the center of Washington in zone 8a[1]. By land area, 56% of the city lies in ZIP code areas rated zone 7b[15].
When is the last frost in Washington, DC?
The median last spring frost is March 29[2]. In 1 of 10 years the last frost comes after April 11[2].
When to plant tomatoes in Washington, DC?
CSU groups tomatoes as very tender vegetables, typically planted 2 or more weeks after the average last frost[11]. In Washington the earliest start by that rule is April 12[11].
When is the first frost in Washington, DC?
The median first fall frost is November 8[3]. In 1 of 10 years it comes before October 26[3].
How long is the growing season in Washington, DC?
In half of years the growing season lasts at least 224 days, and in 9 of 10 years at least 205 days[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Washington, District of Columbia in zone 8a. Zone 8a means an average annual extreme minimum temperature of 10°F to 15°F over 1991 to 2020. The map's modeled value at the city center is 10.9°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 15, in half of years after March 29, and in 1 of 10 years after April 11 (NOAA 1991 to 2020 normals). The median last frost date is March 29. 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 26, in half of years before November 8, and in 9 of 10 years before November 23 (NOAA 1991 to 2020 normals). The median first frost date is November 8. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 205 days in 9 of 10 years, at least 224 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 Natl Arboretum Dc weather station (USC00186350), 2.6 miles from the center of Washington at 50 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 20. 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. Washington, District of Columbia overlaps 40 ZIP code areas. By land area, 56% lies in ZIP code areas rated zone 7b, 43% lies in ZIP code areas rated zone 8a. 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.