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Frost dates and planting calendar for Kent, Washington

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

USDA hardiness zone
8b[1]
Median last spring frost
Mar 20[2]
Median first fall frost
Nov 10[3]
Growing season, median
233 days[4]

The USDA map puts the center of Kent, Washington in zone 8b[1]. The median last spring frost at the Kent weather station is March 20[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Feb 27, half of years Mar 20, 1 in 10 years after Apr 8Last frostmedian Mar 20First fall frost: 9 in 10 years before Nov 26, half of years Nov 10, 1 in 10 years before Oct 26First frostmedian Nov 10Frost riskHardyHardy vegetables: plant Feb 20 to Mar 6Feb 20 to Mar 6Semi-hardySemi-hardy vegetables: plant Mar 6 to Mar 20Mar 6 to Mar 20TenderTender vegetables: plant around Mar 20around Mar 20Very tenderVery tender vegetables: plant from Apr 3from Apr 3
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 dates come from NOAA climate normals for the Kent weather station, using records from 1991 to 2020[5]. In half of years the last spring frost comes after March 20, and in 1 of 10 years it comes after April 8[2]. In half of years the first fall frost comes before November 10, and in 1 of 10 years it comes before October 26[3]. These are odds from past years, 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 February 27 after March 20 after April 8
First fall frost (32°F)[3] before October 26 before November 10 before November 26
  • Hard freeze (28°F): median last spring date February 25, median first fall date November 24[7].
  • Frost-free growing season: at least 207 days in 9 of 10 years, 233 days in half of years and 262 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 100% of years and 28°F or colder in 99.9% of years[8].
  • Weather station: Kent (USC00454169), 2.5 miles from the city center, 30 feet, 28 years of 1991 to 2020 records[5].

When to plant vegetables

Colorado State University Extension wrote its vegetable planting guide for Colorado, and the dates below apply its rules to Kent's median last frost[6]. Hardy vegetables such as broccoli, lettuce, peas and spinach can go in as early as 2 to 4 weeks before the median last frost, which is February 20 to March 6 in Kent[6]. Semi-hardy vegetables such as carrots, beets and potatoes can go in as early as 2 weeks before the median last frost, which is March 6[9]. Tender vegetables such as snap beans and sweet corn can be planted from seed around March 20[10]. Very tender vegetables such as tomatoes and peppers typically start 2 or more weeks after the median last frost, so April 3 is 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 20) is February 20 to March 6[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (March 20) is March 6, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, March 20[10]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (March 20), is April 3[11]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Feb 20 Apr 26 (from transplants)
Cabbage (hardy)[12] Feb 20 May 16 (from transplants)
Kohlrabi (hardy)[12] Feb 20 Apr 11
Lettuce (hardy)[12] Feb 20 Apr 21
Onions (hardy)[12] Feb 20 Jun 10
Peas (hardy)[12] Feb 20 Apr 26
Radishes (hardy)[12] Feb 20 Mar 22
Spinach (hardy)[12] Feb 20 Apr 1
Turnips (hardy)[12] Feb 20 Apr 11
Beets (semi-hardy)[12] Mar 6 May 5
Carrots (semi-hardy)[12] Mar 6 May 15
Cauliflower (semi-hardy)[12] Mar 6 not listed
Parsnips (semi-hardy)[12] Mar 6 May 15
Potatoes (semi-hardy)[12] Mar 6 Jul 9
Swiss chard (semi-hardy)[12] Mar 6 May 5
Snap beans (tender)[12] Mar 20 May 19
Sweet corn (tender)[12] Mar 20 May 19
Cucumbers (tender)[12] Mar 20 May 14
Summer squash (tender)[12] Mar 20 May 9
Cantaloupe (very tender)[12] Apr 3 Jun 27
Eggplant (very tender)[12] Apr 3 Jun 2 (from transplants)
Peppers (very tender)[12] Apr 3 Jun 12 (from transplants)
Tomatoes (very tender)[12] Apr 3 Jun 7 (from transplants)
Winter squash (very tender)[12] Apr 3 Jul 12
Watermelon (very tender)[12] Apr 3 Jun 27
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 8b means the coldest night of each winter averages 15°F to 20°F, based on 1991 to 2020[1]. The zone is about winter lows, not summer heat or frost dates[14]. Kent overlaps 11 ZIP code areas[15]. By land area, 57% lies in areas rated zone 8b and 43% in areas rated zone 9a[15].

Zone 8b: average annual extreme minimum temperature 15°F to 20°F (1991 to 2020)[1]. Modeled value at the city center: 19.5°F[1].

Share of the city's land area by ZIP code zone: zone 8b 57%, zone 9a 43%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
98032[15] 9a 20 to 25°F
98031[15] 8b 15 to 20°F
98030[15] 8b 15 to 20°F
98042[15] 8b 15 to 20°F
98051[15] 8b 15 to 20°F
98092[15] 8b 15 to 20°F
98038[15] 8b 15 to 20°F
98055[15] 9a 20 to 25°F
98198[15] 9a 20 to 25°F
98002[15] 8b 15 to 20°F
98058[15] 8b 15 to 20°F

Questions people ask

What growing zone is Kent, Washington?
The 2023 USDA map puts the center of Kent in zone 8b[1]. By land area, 43% of the city lies in ZIP code areas rated zone 9a[15].
When is the last frost in Kent?
The median last spring frost is March 20, so in half of years the last frost comes after that date[2]. In 1 of 10 years it comes after April 8[2].
When to plant tomatoes in Kent?
CSU Extension says very tender vegetables like tomatoes typically start 2 or more weeks after the average last spring frost, which gives April 3 as the earliest start[11]. CSU's guide was written for Colorado[11].
When is the first frost in Kent?
The median first fall frost is November 10[3]. In 1 of 10 years it comes before October 26[3].
How long is the growing season in Kent?
The growing season is at least 233 days in half of years[4]. In 1 of 10 years it is at least 262 days, and in 9 of 10 years it is at least 207 days[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Kent, Washington in zone 8b. Zone 8b means an average annual extreme minimum temperature of 15°F to 20°F over 1991 to 2020. The map's modeled value at the city center is 19.5°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 27, in half of years after March 20, and in 1 of 10 years after April 8 (NOAA 1991 to 2020 normals). The median last frost date is March 20. 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 10, and in 9 of 10 years before November 26 (NOAA 1991 to 2020 normals). The median first frost date is November 10. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 207 days in 9 of 10 years, at least 233 days in half of years, and at least 262 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Kent weather station (USC00454169), 2.5 miles from the center of Kent at 30 feet, using 28 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 25 and the median first fall date is November 24. 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 99.9% 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. Kent, Washington overlaps 11 ZIP code areas. By land area, 57% lies in ZIP code areas rated zone 8b, 43% 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.