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Frost dates and planting calendar for Newark, Delaware

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
Apr 7[2]
Median first fall frost
Nov 2[3]
Growing season, median
208 days[4]

Newark, Delaware sits in USDA hardiness zone 7b[1]. The median last spring frost here is April 7[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Mar 26, half of years Apr 7, 1 in 10 years after Apr 21Last frostmedian Apr 7First fall frost: 9 in 10 years before Nov 17, half of years Nov 2, 1 in 10 years before Oct 19First frostmedian Nov 2Frost riskHardyHardy vegetables: plant Mar 10 to Mar 24Mar 10 to Mar 24Semi-hardySemi-hardy vegetables: plant Mar 24 to Apr 7Mar 24 to Apr 7TenderTender vegetables: plant around Apr 7around Apr 7Very tenderVery tender vegetables: plant from Apr 21from Apr 21
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.

The frost dates here come from NOAA climate normals for the Newark Ag Farm station, using records from 1991 to 2020[5]. In half of years the last spring frost comes after April 7, and in 1 of 10 years it comes after April 21[2]. In half of years the first fall frost comes before November 2, and in 1 of 10 years it comes before October 19[3]. These are odds from past records and not a forecast, so any year can be earlier or later[2].

Frost Likely (9 in 10 years) Even odds (5 in 10) Unlikely (1 in 10)
Last spring frost (32°F)[2] after March 26 after April 7 after April 21
First fall frost (32°F)[3] before October 19 before November 2 before November 17
  • Hard freeze (28°F): median last spring date March 27, median first fall date November 13[7].
  • Frost-free growing season: at least 190 days in 9 of 10 years, 208 days in half of years and 228 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: Newark Ag Farm (USC00076410), 0.9 miles from the city center, 106 feet, 15 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension's planting guide was written for Colorado, so these dates are simple arithmetic and not advice from the source[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 10 to March 24[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 March 24[9]. Tender vegetables such as snap beans and sweet corn can start from seed around the median last frost date, April 7[10]. Very tender vegetables such as tomatoes and peppers typically wait 2 or more weeks after it, so the earliest start is April 21[11].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (April 7) is March 10 to March 24[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (April 7) is March 24, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, April 7[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (April 7), is April 21[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Mar 10 May 14 (from transplants)
Cabbage (hardy)[12] Mar 10 Jun 3 (from transplants)
Kohlrabi (hardy)[12] Mar 10 Apr 29
Lettuce (hardy)[12] Mar 10 May 9
Onions (hardy)[12] Mar 10 Jun 28
Peas (hardy)[12] Mar 10 May 14
Radishes (hardy)[12] Mar 10 Apr 9
Spinach (hardy)[12] Mar 10 Apr 19
Turnips (hardy)[12] Mar 10 Apr 29
Beets (semi-hardy)[12] Mar 24 May 23
Carrots (semi-hardy)[12] Mar 24 Jun 2
Cauliflower (semi-hardy)[12] Mar 24 not listed
Parsnips (semi-hardy)[12] Mar 24 Jun 2
Potatoes (semi-hardy)[12] Mar 24 Jul 27
Swiss chard (semi-hardy)[12] Mar 24 May 23
Snap beans (tender)[12] Apr 7 Jun 6
Sweet corn (tender)[12] Apr 7 Jun 6
Cucumbers (tender)[12] Apr 7 Jun 1
Summer squash (tender)[12] Apr 7 May 27
Cantaloupe (very tender)[12] Apr 21 Jul 15
Eggplant (very tender)[12] Apr 21 Jun 20 (from transplants)
Peppers (very tender)[12] Apr 21 Jun 30 (from transplants)
Tomatoes (very tender)[12] Apr 21 Jun 25 (from transplants)
Winter squash (very tender)[12] Apr 21 Jul 30
Watermelon (very tender)[12] Apr 21 Jul 15
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

The zone number comes from the average coldest night of each winter from 1991 to 2020, and not from summer heat or frost dates[14]. Zone 7b means an average annual extreme minimum of 5°F to 10°F[1]. All of Newark'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: 5.9°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
19711[15] 7b 5 to 10°F
19713[15] 7b 5 to 10°F
19716[15] 7b 5 to 10°F
19717[15] 7b 5 to 10°F
19702[15] 7b 5 to 10°F

Questions people ask

What growing zone is Newark, Delaware?
The 2023 USDA map puts the center of Newark 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 Newark, Delaware?
In half of years the last spring frost comes after April 7, and in 9 of 10 years it comes after March 26[2]. In 1 of 10 years it comes after April 21[2].
When to plant tomatoes in Newark, Delaware?
CSU Extension typically says 2 or more weeks after the average last frost for tomatoes[11]. Using the median last frost, the earliest start is April 21[11].
When is the first frost in Newark, Delaware?
In half of years the first fall frost comes before November 2[3]. In 1 of 10 years it comes before October 19[3].
How long is the growing season in Newark, Delaware?
The growing season is at least 208 days in half of years[4]. It is at least 190 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Newark, Delaware 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 5.9°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 26, in half of years after April 7, and in 1 of 10 years after April 21 (NOAA 1991 to 2020 normals). The median last frost date is April 7. 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 19, in half of years before November 2, and in 9 of 10 years before November 17 (NOAA 1991 to 2020 normals). The median first frost date is November 2. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 190 days in 9 of 10 years, at least 208 days in half of years, and at least 228 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Newark Ag Farm weather station (USC00076410), 0.9 miles from the center of Newark at 106 feet, using 15 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 27 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. Newark, Delaware overlaps 5 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.