When to Plant in Seattle, WA: Planting Calendar & Frost Dates
Quick answer
In Seattle (ZIP 98101), the median last spring frost is Mar 13 and the first fall frost is Nov 17. Start tomato seeds indoors Apr 3 – Apr 10 and transplant them around mid-May, once the soil is 50°F or warmer (WSU Extension King County); sow peas Jan 30 – Feb 13; plant garlic Nov 3 – Dec 8.
For ZIP 98101 in Seattle, the nearest NOAA weather station with freeze records is Seattle Boeing Field (NOAA name: Seattle Boeing Fld, WA), 5.8 miles away. Its median last spring frost (32°F, NOAA 1991–2020) is Mar 13 and its median first fall frost is Nov 17, leaving about 249 frost-free days. ZIP 98101 is in USDA hardiness zone 9a. The last frost here comes 17 days later than the zone 9 median (Feb 24), and the season is 33 days shorter than the zone’s typical 282 days. Across Washington’s 605 ZIP codes with frost dates, the median last frost is Apr 15, so Seattle’s comes 33 days earlier than that.
Station and dates: NOAA NCEI U.S. Climate Normals 1991–2020, 32°F at 50% probability, for the station nearest the center of ZIP 98101. Zone: 2023 USDA Plant Hardiness Zone Map (PRISM data by ZIP code). Outside Delaware, Maryland, Pennsylvania, New Jersey and Virginia the planner uses the nearest NOAA station with freeze data, which can be at a different elevation from your yard.
Next 30 days in Seattle
See what to plant this month in the planner for ZIP 98101.
Key planting dates for Seattle
| Key date | When in Seattle | How it is counted |
|---|---|---|
| Sow peas | Jan 30 – Feb 13 | 4–6 weeks before last frost (Mar 13) |
| Start tomatoes indoors | Apr 3 – Apr 10 | 5–6 weeks before the mid-May transplant date (WSU Pacific Northwest Gardener’s Handbook: 5–6 weeks to transplant size) |
| Transplant tomatoes | Around mid-May | Around mid-May, once the soil is 50°F or warmer (WSU Extension King County) |
| Sow beans and squash | Late spring, once the soil is 65°F | WSU Extension FS088E; WSU gives no calendar date |
| Sow fall lettuce | Sep 22 – Oct 6 | 6–8 weeks before first fall frost (Nov 17) |
| Plant garlic | Nov 3 – Dec 8 | 2 weeks before to 3 weeks after first fall frost, while the soil is still workable (SDSU, Illinois, Virginia Tech) (Nov 17) |
| Plant tulip bulbs | Nov 3 – Dec 15 | 2 weeks before to 4 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) (Nov 17) |
WSU Extension’s guidance for Seattle gardens
Tomatoes: WSU Extension King County Master Gardeners: “Plant transplants after the soil temperature is 50 degrees or above, typically around the middle of May.” And: “Even though some nurseries begin to stock tomatoes in early April, it is far too early to plant them in the ground at that time.” Our usual frost-date rule (1–2 weeks after the NOAA median last frost at Seattle Boeing Field, Mar 13) would give Mar 20 – Mar 27; for Seattle ZIP codes the planner and this page use WSU’s mid-May timing instead.
Other warm-season crops: peppers, eggplant, cucumbers, squash, sweet corn and beans on this page follow WSU Extension’s soil-temperature timing rather than the NOAA median last frost (Mar 13); the rule under each date names the source. We have no sourced western Washington date for basil or pumpkins, so the calendar says so. WSU’s statewide vegetable guide notes that “the cool springs in western Washington can make it difficult to get good germination of crops that prefer warm soils.”
- Pick quick tomatoes: “To ripen well in our climate, choose tomatoes with “days to maturity” of 75 days or less for best results.” WSU’s tomato fact sheet lists “Time to transplant: After the last frost date in May or June” and “Growing season: May through October”.
- A long, cool season: “Even though we have a long growing season, the weather is relatively cool, so you may not be able to grow some of the vegetables that thrive in hotter parts of the country. For example, tomatoes can be successfully grown here, but short-season varieties should be selected.”
- Mild winters: “Many cool-season crops can be grown throughout the winter in areas west of the Cascades, depending on the microclimate.”
- Garlic: “Plant garlic in early to mid-fall (September to October) in eastern Washington gardens and late fall (November) in western Washington gardens.” Our frost-date window for ZIP 98101 is Nov 3 – Dec 8.
- Zones in King County: “Most of King County is Zone 9 (20-30° F) or Zone 8 (10-20° F), but the eastern part is Zone 7 (0-10° F) or Zone 6 (-10 to 0° F).” ZIP 98101 is zone 9a.
Sources: WSU Extension King County Master Gardeners, Tip Sheet #7: Tomatoes; WSU FS145E, Growing Tomatoes in Home Gardens; WSU Extension King County Master Gardeners, Tip Sheet #3: New to Gardening in Western WA?; WSU EM057E, Home Vegetable Gardening in Washington; WSU FS162E, Growing Garlic in Home Gardens.
Seattle vegetable and flower planting calendar
Every date range below is counted from Seattle’s median frost dates (Mar 13 and Nov 17) with the same rules as our planner, and rows run in calendar order. In about half of years a frost still comes after the spring date.
Tulips in western Washington: WSU Extension says gardeners plant tulips, daffodils, hyacinths and crocus outdoors in western Washington from October through mid-December, for bloom in March and April, and planting them out in the landscape needs no special preparation, so the fall tulip dates below apply here (WSU Extension Snohomish County, Fact Sheet #67).
| Plant | Task | Dates (and how they are counted) | Expected harvest (estimate) |
|---|---|---|---|
| Broccoli | Start indoors | Jan 2 – Jan 168–10 weeks before last frost (avg. Mar 13) | — |
| Cabbage | Start indoors | Jan 2 – Jan 168–10 weeks before last frost (avg. Mar 13) | — |
| Kale | Start indoors | Jan 2 – Jan 168–10 weeks before last frost (avg. Mar 13) | — |
| Peas | Direct sow | Jan 30 – Feb 134–6 weeks before last frost (avg. Mar 13) | Mar 31 – May 460–80 days from seeding |
| Spinach | Direct sow | Jan 30 – Feb 134–6 weeks before last frost (avg. Mar 13) | Mar 16 – Apr 1445–60 days from seeding |
| Radishes | Direct sow | Feb 6 – Feb 272–5 weeks before last frost (avg. Mar 13) | Feb 26 – Mar 2920–30 days from seeding |
| Lettuce | Direct sow | Feb 13 – Feb 272–4 weeks before last frost (avg. Mar 13) | Apr 14 – May 1860–80 days from seeding |
| Onions (sets/transplants) | Plant sets/transplants | Feb 13 – Feb 272–4 weeks before last frost (avg. Mar 13) | May 9 – Jun 2785–120 days from planting |
| Broccoli | Transplant | Feb 13 – Feb 272–4 weeks before last frost (avg. Mar 13) | Apr 4 – May 850–70 days from transplanting |
| Cabbage | Transplant | Feb 13 – Feb 272–4 weeks before last frost (avg. Mar 13) | Apr 24 – May 2870–90 days from transplanting |
| Kale | Transplant | Feb 13 – Feb 272–4 weeks before last frost (avg. Mar 13) | — |
| Marigolds | Start indoors | Feb 20 – Mar 130–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) (avg. Mar 13) | — |
| Zinnias | Start indoors | Feb 20 – Mar 130–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) (avg. Mar 13) | — |
| Potatoes | Plant seed potatoes | Feb 27 – Mar 61–2 weeks before last frost (avg. Mar 13) | May 23 – Jun 2485–110 days from planting |
| Marigolds | Direct sow / transplant | Mar 13 – Mar 27from the last frost to 2 weeks after (Univ. of Idaho) (avg. Mar 13) | — |
| Zinnias | Direct sow / transplant | Mar 13 – Mar 27from the last frost to 2 weeks after (Univ. of Idaho) (avg. Mar 13) | — |
| Peppers | Start indoors | Mar 20 – Apr 36–8 weeks before transplanting (WSU Extension FS220E) | — |
| Eggplant | Start indoors | 6–9 weeks before you transplantWSU Pacific Northwest Gardener’s Handbook, weeks to transplant size; no date because WSU gives no western Washington eggplant date | — |
| Basil | Start indoors | No sourced dateWe have no WSU date for starting basil in western Washington | — |
| Tomatoes | Start indoors | Apr 3 – Apr 105–6 weeks before the mid-May transplant date (WSU Pacific Northwest Gardener’s Handbook: 5–6 weeks to transplant size) | — |
| Sweet corn | Direct sow | Near the end of AprilOnce the soil reaches 60°F and there is no danger of frost; WSU says planting usually takes place near the end of April in western Washington (WSU Extension FS104E) | Jun 26 – Jul 2965–90 days from seeding |
| Tomatoes | Transplant | Around mid-MayAround mid-May, once the soil is 50°F or warmer (WSU Extension King County) | Jul 24 – Aug 1370–90 days from transplanting |
| Peppers | Transplant | Mid to late MayOnce the soil is 65–70°F (WSU Extension FS220E); WSU gives mid to late May for direct seeding peppers | Jul 19 – Aug 1465–75 days from transplanting |
| Eggplant | Transplant | When the soil is 60°F or warmerWSU Extension FS149E: wait for the soil to warm to 60°F; row covers or black plastic help. No sourced western Washington date | — |
| Cucumbers | Direct sow | Mid to late MayOnce the soil is at least 55°F (WSU Extension) | Jun 24 – Aug 440–65 days from seeding |
| Squash | Direct sow | Mid to late MayMid to late May, after the last killing frost (WSU Extension) | Jun 24 – Jul 2040–50 days from seeding |
| Beans (bush & pole) | Direct sow | Late spring, once the soil is 65°FWSU Extension FS088E; WSU gives no calendar date | — |
| Pumpkins | Direct sow | No sourced dateWe have no WSU date for pumpkins in western Washington | — |
| Basil | Transplant | No sourced dateWe have no current WSU date for planting basil out in western Washington | — |
| Broccoli | Fall transplant | Aug 25 – Sep 810–12 weeks before first fall frost (avg. Nov 17) | Oct 14 – Nov 1750–70 days from transplanting |
| Cabbage | Fall transplant | Aug 25 – Sep 810–12 weeks before first fall frost (avg. Nov 17) | Nov 3 – Dec 770–90 days from transplanting |
| Kale | Fall sow | Sep 8 – Sep 228–10 weeks before first fall frost (avg. Nov 17) | Oct 28 – Dec 150–70 days from seeding |
| Lettuce | Fall sow | Sep 22 – Oct 66–8 weeks before first fall frost (avg. Nov 17) | Nov 21 – Dec 2560–80 days from seeding |
| Spinach | Fall sow | Sep 29 – Oct 204–7 weeks before first fall frost (Virginia Tech) (avg. Nov 17) | Nov 13 – Dec 1945–60 days from seeding |
| Radishes | Fall sow | Oct 6 – Oct 204–6 weeks before first fall frost (avg. Nov 17) | Oct 26 – Nov 1920–30 days from seeding |
| Daffodils | Fall plant bulbs | Oct 20 – Dec 14 weeks before to 2 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) (avg. Nov 17) | — |
| Tulips | Fall plant bulbs | Nov 3 – Dec 152 weeks before to 4 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) (avg. Nov 17) | — |
| Garlic | Fall plant cloves | Nov 3 – Dec 82 weeks before to 3 weeks after first fall frost, while the soil is still workable (SDSU, Illinois, Virginia Tech) (avg. Nov 17) | Jul 11 – Sep 4 (next year)250–270 days from planting |
How we count planting dates: the weeks before or after frost for each crop come from university extension planting guides: UNH Extension, When to Plant Your Vegetable Garden; Rutgers FS787, Starting Vegetable Seeds Indoors; Virginia Tech 426-331, Home Garden Vegetable Planting Guide; University of Maryland Extension, Vegetable Planting Calendar; and University of Idaho CIS 1209 (marigolds and zinnias). Bulb windows approximate Rutgers’ rule to plant when soil falls below 60°F (FS1220), and garlic follows SDSU, Illinois and Virginia Tech. Temperature notes: UMD (potatoes), UMN (sweet corn), UC ANR (peppers, hardening off), UMN (eggplant), Colorado State (tomatoes) and SDSU (hardening off).
Harvest estimates add days to harvest from these sources to each planting window, and stop at the first fall frost for frost-tender crops: UF/IFAS Extension, Florida Vegetable Gardening Guide (SP103/VH021), Table 1, “Days to Harvest”; University of Maryland Extension, Growing Onions in a Home Garden; University of Maryland Extension, Growing Garlic in a Home Garden; University of Maryland Extension, Growing Basil in a Home Garden.
Frost dates across Seattle’s ZIP codes
Across Seattle’s 27 ZIP codes, the median last spring frost ranges from Mar 8 to Mar 13 and the median first fall frost from Nov 17 to Nov 23, depending on which of 2 NOAA stations is nearest. This page uses ZIP 98101, which is in the group most Seattle ZIP codes share.
| Nearest NOAA station | Last spring frost | First fall frost | Seattle ZIP codes |
|---|---|---|---|
| Seattle Boeing Field (NOAA name: Seattle Boeing Fld, WA) | Mar 13 | Nov 17 | 15: 98101, 98104, 98106, 98108, 98116, 98118, 98121, 98122, 98126, 98134, 98136, 98144, 98154, 98164, 98174 |
| Seattle Sand Pt Wsfo | Mar 8 | Nov 23 | 12: 98102, 98103, 98105, 98107, 98109, 98112, 98115, 98117, 98119, 98125, 98195, 98199 |
Which ZIP codes count as Seattle: the 27 ZIP Code Tabulation Areas (2020 ZCTAs) with at least half of their land area inside Seattle city limits, from the U.S. Census Bureau, 2020 ZCTA to Place Relationship File. ZCTAs are the Census Bureau’s approximations of USPS ZIP Code areas, so this list may not match every USPS ZIP code. Each ZIP code’s dates are the ones our planner shows for it.
How Seattle compares
| Area | Median last spring frost | Median first fall frost | Frost-free days |
|---|---|---|---|
| Seattle (ZIP 98101) | Mar 13 | Nov 17 | 249 |
| Washington (median of 605 ZIP codes) | Apr 15 | Oct 25 | 193 |
| USDA zone 9 (median of 3,241 ZIP codes) | Feb 24 | Dec 3 | 282 |
How this table is built: each ZIP code is matched to its nearest NOAA 1991–2020 freeze-data station (within 60 miles); state and zone rows are medians across those ZIP codes. Zones are the 2023 USDA zones by ZIP code (PRISM).
More for Seattle gardeners
- Your own ZIP: open the planner for ZIP 98101 and change the ZIP to yours for its own station and dates.
- Washington: When to plant in Washington, with frost dates across the state.
- USDA zone 9a: our zone 9 planting guide.
- Frost tonight? How to protect plants from frost.
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Frequently asked questions
When is the last frost in Seattle?
For ZIP 98101 in Seattle, the nearest NOAA 1991–2020 normals station (Seattle Boeing Field, 5.8 miles away) has a median last spring frost (32°F) of Mar 13. Across Seattle’s 27 ZIP codes it ranges from Mar 8 to Mar 13. In about half of years a frost still comes after that date, so tender plants are safer 1–2 weeks later.
When should I plant tomatoes in Seattle?
WSU Extension King County says to plant transplants after the soil is 50°F or warmer, typically around the middle of May, and calls early April far too early. Start seeds indoors Apr 3 – Apr 10.
What is the first fall frost date in Seattle?
The median first fall frost (32°F) for ZIP 98101 is Nov 17, about 249 days after the last spring frost. Across Seattle’s ZIP codes it ranges from Nov 17 to Nov 23. Sow fall lettuce Sep 22 – Oct 6 and plant garlic Nov 3 – Dec 8.
What USDA zone is Seattle in?
ZIP 98101 in Seattle is in USDA hardiness zone 9a on the 2023 USDA map (by ZIP code, via PRISM). Hardiness zones describe winter low temperatures, not frost dates.
Sources
- NOAA National Centers for Environmental Information: U.S. Climate Normals 1991–2020
- USDA Agricultural Research Service, Plant Hardiness Zone Map: 2023 USDA Plant Hardiness Zone Map
- Washington State University Extension: WSU Extension King County Master Gardeners, Tip Sheet #7: Tomatoes; WSU FS145E, Growing Tomatoes in Home Gardens; WSU Extension King County Master Gardeners, Tip Sheet #3: New to Gardening in Western WA?; WSU EM057E, Home Vegetable Gardening in Washington; WSU FS162E, Growing Garlic in Home Gardens; WSU Extension Snohomish County, Fact Sheet #67
- UNH Extension: When to Plant Your Vegetable Garden
- Rutgers NJAES Cooperative Extension: Rutgers FS787, Starting Vegetable Seeds Indoors; FS1220: Spring Flowering Bulbs (Rutgers NJAES)
- Virginia Cooperative Extension (Virginia Tech): Virginia Cooperative Extension 426-331, Virginia’s Home Garden Vegetable Planting Guide
- University of Maryland Extension: Vegetable Planting Calendar; Growing Potatoes in a Home Garden; Growing Onions in a Home Garden; Growing Garlic in a Home Garden; Growing Basil in a Home Garden
- University of Idaho Extension: CIS 1209
- South Dakota State University Extension: Planting Garlic; Harden Your Transplants Prior To Planting Your Garden
- University of Illinois Extension: Ready, Set, Garlic!
- University of Minnesota Extension: Growing sweet corn in home gardens; Growing eggplant in home gardens
- University of California Agriculture and Natural Resources (UC ANR): Growing Peppers
- Colorado State University Extension: Growing tomatoes
- UF/IFAS Extension: Florida Vegetable Gardening Guide (SP103/VH021), Table 1, “Days to Harvest”
- U.S. Census Bureau: 2020 ZCTA to Place Relationship File