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Frost dates and planting calendar for Portland, Oregon

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 13[2]
Median first fall frost
Nov 19[3]
Growing season, median
247 days[4]

The center of Portland sits in USDA hardiness zone 9a[1]. In half of years the last spring frost at Portland International Airport comes after March 13, the median date[2].

Frost dates

JanFebMarAprMayJunJulAugSepOctNovDecLast spring frost: 9 in 10 years after Feb 22, half of years Mar 13, 1 in 10 years after Apr 1Last frostmedian Mar 13First fall frost: 9 in 10 years before Dec 10, half of years Nov 19, 1 in 10 years before Oct 29First frostmedian Nov 19Frost riskHardyHardy vegetables: plant Feb 13 to Feb 27Feb 13 to Feb 27Semi-hardySemi-hardy vegetables: plant Feb 27 to Mar 13Feb 27 to Mar 13TenderTender vegetables: plant around Mar 13around Mar 13Very tenderVery tender vegetables: plant from Mar 27from Mar 27
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 from NOAA records for the Portland International Airport station, 1991 to 2020[5]. In half of years the last spring frost comes after March 13, and in 1 of 10 years it comes after April 1[2]. In 1 of 10 years the first fall frost comes before October 29, and in half of years before November 19[3]. The time between them is at least 247 days in half of years[4]. These are chances, not a forecast, so 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 22 after March 13 after April 1
First fall frost (32°F)[3] before October 29 before November 19 before December 10
  • Hard freeze (28°F): median last spring date February 16, median first fall date December 5[7].
  • Frost-free growing season: at least 219 days in 9 of 10 years, 247 days in half of years and 277 days in 1 of 10 years[4].
  • The low reached 32°F or colder in 100% of years and 28°F or colder in 98.4% of years[8].
  • Weather station: Portland International Airport (USW00024229), 4.4 miles from the city center, 19 feet, 27 years of 1991 to 2020 records[5].

When to plant vegetables

The planting dates on this page come from Colorado State University Extension's vegetable guide, which was written for Colorado[6]. GardenFacts uses the NOAA median last frost of March 13 as the average last frost[6]. Hardy crops like peas, lettuce and spinach can go in as early as February 13 to February 27[6]. Semi-hardy crops like beets, carrots and potatoes can go in as early as February 27, up to March 13[9]. Very tender crops like tomatoes, peppers and eggplant typically wait 2 or more weeks after the median last frost, so March 27 is the earliest start[10].

  • Hardy (broccoli, cabbage, kohlrabi, lettuce, onions, peas, radishes, spinach, turnips): as early as 2 to 4 weeks before the median last frost (March 13) is February 13 to February 27[6]
  • Semi-hardy (beets, carrots, cauliflower, parsnips, potatoes, Swiss chard): as early as 2 weeks before the median last frost (March 13) is February 27, up to the median date itself[9]
  • Tender (snap beans, sweet corn, cucumbers, summer squash): from seed around the median last frost date, March 13[11]
  • Very tender (cantaloupe, eggplant, peppers, tomatoes, winter squash, watermelon): the earliest start, two weeks after the median last frost (March 13), is March 27[10]
Vegetable (CSU group) Plant from First harvest around
Broccoli (hardy)[12] Feb 13 Apr 19 (from transplants)
Cabbage (hardy)[12] Feb 13 May 9 (from transplants)
Kohlrabi (hardy)[12] Feb 13 Apr 4
Lettuce (hardy)[12] Feb 13 Apr 14
Onions (hardy)[12] Feb 13 Jun 3
Peas (hardy)[12] Feb 13 Apr 19
Radishes (hardy)[12] Feb 13 Mar 15
Spinach (hardy)[12] Feb 13 Mar 25
Turnips (hardy)[12] Feb 13 Apr 4
Beets (semi-hardy)[12] Feb 27 Apr 28
Carrots (semi-hardy)[12] Feb 27 May 8
Cauliflower (semi-hardy)[12] Feb 27 not listed
Parsnips (semi-hardy)[12] Feb 27 May 8
Potatoes (semi-hardy)[12] Feb 27 Jul 2
Swiss chard (semi-hardy)[12] Feb 27 Apr 28
Snap beans (tender)[12] Mar 13 May 12
Sweet corn (tender)[12] Mar 13 May 12
Cucumbers (tender)[12] Mar 13 May 7
Summer squash (tender)[12] Mar 13 May 2
Cantaloupe (very tender)[12] Mar 27 Jun 20
Eggplant (very tender)[12] Mar 27 May 26 (from transplants)
Peppers (very tender)[12] Mar 27 Jun 5 (from transplants)
Tomatoes (very tender)[12] Mar 27 May 31 (from transplants)
Winter squash (very tender)[12] Mar 27 Jul 5
Watermelon (very tender)[12] Mar 27 Jun 20
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 is based on the average coldest winter night, not on summer heat or frost dates[14]. Zone 9a means an average annual extreme minimum of 20°F to 25°F[1]. Portland spans more than one zone[15]. By land area, 67% lies in ZIP code areas rated zone 9a and 33% in areas rated zone 8b[15].

Zone 9a: average annual extreme minimum temperature 20°F to 25°F (1991 to 2020)[1]. Modeled value at the city center: 20.7°F[1].

Share of the city's land area by ZIP code zone: zone 9a 67%, zone 8b 33%[15].

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

Zone by ZIP code
ZIP code Zone Coldest night range
97203[15] 9a 20 to 25°F
97219[15] 8b 15 to 20°F
97217[15] 9a 20 to 25°F
97210[15] 8b 15 to 20°F
97220[15] 9a 20 to 25°F
97211[15] 9a 20 to 25°F
97236[15] 9a 20 to 25°F
97230[15] 9a 20 to 25°F
97218[15] 9a 20 to 25°F
97202[15] 9a 20 to 25°F
97266[15] 9a 20 to 25°F
97206[15] 9a 20 to 25°F
97231[15] 8b 15 to 20°F
97213[15] 8b 15 to 20°F
97229[15] 8b 15 to 20°F
97239[15] 8b 15 to 20°F
97221[15] 8b 15 to 20°F
97233[15] 9a 20 to 25°F
97214[15] 9a 20 to 25°F
97212[15] 8b 15 to 20°F
97216[15] 9a 20 to 25°F
97215[15] 9a 20 to 25°F
97201[15] 8b 15 to 20°F
97232[15] 9a 20 to 25°F
97227[15] 9a 20 to 25°F
97209[15] 9a 20 to 25°F
97205[15] 8b 15 to 20°F
97086[15] 8b 15 to 20°F
97204[15] 9a 20 to 25°F
97035[15] 9a 20 to 25°F

Questions people ask

What growing zone is Portland, Oregon?
The 2023 USDA map puts the center of Portland in zone 9a[1]. By land area, 33% of the city lies in ZIP code areas rated zone 8b[15].
When is the last frost in Portland, Oregon?
The median last spring frost is March 13[2]. In 1 of 10 years the last frost comes after April 1[2].
When to plant tomatoes in Portland, Oregon?
Colorado State University Extension says tomatoes typically go in 2 or more weeks after the average last spring frost[10]. The GardenFacts calculation, taking the NOAA median last frost of March 13 as the average last frost, puts the earliest start for Portland at March 27[10].
When is the first frost in Portland, Oregon?
The median first fall frost is November 19[3]. In 1 of 10 years it comes before October 29[3].
How long is the growing season in Portland, Oregon?
The time between the last spring and first fall frost is at least 247 days in half of years[4]. It is at least 219 days in 9 of 10 years[4].

Facts and sources

  1. The 2023 USDA Plant Hardiness Zone Map puts the center of Portland, Oregon 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 20.7°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 22, in half of years after March 13, and in 1 of 10 years after April 1 (NOAA 1991 to 2020 normals). The median last frost date is March 13. 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 29, in half of years before November 19, and in 9 of 10 years before December 10 (NOAA 1991 to 2020 normals). The median first frost date is November 19. NOAA Climate Normals 1991-2020
  4. Growing season (days between the last spring and first fall 32°F frost) at this station: at least 219 days in 9 of 10 years, at least 247 days in half of years, and at least 277 days in 1 of 10 years. NOAA Climate Normals 1991-2020
  5. Frost dates on this page come from NOAA climate normals for the Portland International Airport weather station (USW00024229), 4.4 miles from the center of Portland at 19 feet, using 27 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 16 and the median first fall date is December 5. 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 98.4% 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 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
  11. 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
  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. Portland, Oregon overlaps 36 ZIP code areas. By land area, 67% lies in ZIP code areas rated zone 9a, 33% lies in ZIP code areas rated zone 8b. 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.