USDA zone 9a in Oregon
USDA plant hardiness zone 9a covers 29 locations across Oregon (average annual extreme minimum 20 to 25 °F): Beaver, OR, Beavercreek, OR, Cannon Beach, OR, Coquille, OR, Depoe Bay, OR, Dexter, OR, and 23 more. Average last spring frost across this group ranges February 15 (Mapleton) to May 20 (Siletz), and growing seasons run 145–306 days (Toledo to Toledo) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Oregon location's own frost dates; the printable planting calendar uses Lookingglass, this group's median-season location.
- USDA zone
- 9a20 to 25 °F
- Last frost range
- Feb 15–May 20avg, 32°F
- First frost range
- Oct 8–Dec 16avg, 32°F
- Growing season range
- 145–306days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Beaver | — | Cloverdale | Mar 17 | Nov 22 | 251 |
| Beavercreek | Happy Valley, Lake Oswego, Tualatin, West Linn, Milwaukie, Oak Grove, +1 more | Oregon City | Mar 18 | Nov 18 | 244 |
| Cannon Beach | Neahkahnie | Seaside | Apr 2 | Nov 12 | 223 |
| Coquille | Myrtle Point | Coquille City | Mar 28 | Nov 6 | 225 |
| Depoe Bay | — | Newport 3n | Mar 12 | Dec 10 | 271 |
| Dexter | Lowell | Lookout Pt Dam | Mar 7 | Nov 27 | 263 |
| Dunes | Heceta Beach, Reedsport, Mapleton, Gardiner | Honeyman Sp | Mar 28 | Nov 22 | 237 |
| Elkton | — | Elkton 1sw | Apr 11 | Nov 6 | 209 |
| Lookingglass * | — | Roseburg Kqen | Mar 23 | Nov 18 | 237 |
| Lookingglass | Dillard | Riddle | Mar 31 | Nov 6 | 221 |
| Mapleton | — | Mapleton | Feb 15 | Dec 9 | 306 |
| Melrose | — | Winchester | Mar 31 | Nov 5 | 215 |
| Myrtle Point | Langlois | Langlois #2 | Mar 16 | Nov 29 | 258 |
| Portland | Beaverton, Tigard | Portland Kgw-tv | Feb 25 | Dec 1 | 280 |
| Portland | — | Portland Intl Ap | Mar 13 | Nov 19 | 247 |
| Portland | Gresham, Happy Valley, Fairview, Maywood Park | Portland Wfo | Mar 13 | Nov 22 | 251 |
| Portland | — | Vancouver Pearson Ap | Mar 29 | Nov 9 | 223 |
| Powers | — | Illahe | Mar 30 | Nov 17 | 233 |
| Powers | — | Powers | Mar 21 | Nov 14 | 241 |
| Rockaway Beach | Oceanside, Garibaldi, Manzanita, Wheeler, Fairview | Tillamook | Apr 22 | Oct 21 | 183 |
| Rose Lodge | Lincoln Beach, Depoe Bay, Neskowin, Neotsu, Siletz | Otis 2 Ne | Apr 4 | Nov 16 | 227 |
| Saunders Lake | Lakeside, Bunker Hill | North Bend Rgnl Ap | Feb 21 | Dec 9 | 294 |
| Siletz | — | Laurel Mtn | May 20 | Oct 23 | 157 |
| Toledo | — | Corvallis Water Bureau | May 15 | Oct 8 | 145 |
| Toledo | Bayshore | Newport 1 Se | Feb 19 | Dec 16 | 306 |
| Troutdale | — | Troutdale | Mar 26 | Nov 17 | 237 |
| Waldport | — | Alsea Fh (fall Creek) | Apr 13 | Nov 3 | 202 |
| Waldport | Yachats | Yachats | Feb 19 | Dec 11 | 303 |
| Warrenton | Jeffers Gardens | Astoria Rgnl Ap | Mar 26 | Nov 11 | 232 |
* Lookingglass is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Lookingglass, representative)
Computed from Lookingglass's average frost dates — the median-season location in this Oregonzone 9a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Jan 26 – Feb 9 | Mar 30 – Apr 6 | May 29 – Jun 18 | — | matures comfortably |
| Pepper | Very tender | Jan 12 – Jan 26 | Apr 6 – Apr 13 | Jun 5 – Jul 5 | — | matures comfortably |
| Cucumber | Tender | Feb 23 – Mar 2 | Mar 30 – Apr 6 | May 19 – Jun 8 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Mar 30 – Apr 6 | May 14 – May 29 | — | matures comfortably |
| Bush bean | Tender | — | Mar 30 – Apr 6 | May 19 – May 29 | Sep 19 – Sep 29 | matures comfortably |
| Sweet corn | Tender | — | Mar 23 – Apr 6 | May 22 – Jun 21 | — | matures comfortably |
| Basil | Very tender | Feb 9 – Feb 23 | Mar 30 – Apr 6 | Apr 29 – May 14 | — | matures comfortably |
| Lettuce | Half-hardy | Feb 9 – Feb 23 | Feb 23 – Mar 9 | Apr 9 – Apr 24 | Sep 5 – Sep 20 | matures comfortably |
| Pea | Hardy | — | Feb 9 – Feb 23 | Apr 5 – Apr 20 | Aug 26 – Sep 10 | matures comfortably |
| Spinach | Hardy | — | Feb 9 – Feb 23 | Mar 21 – Mar 31 | Sep 15 – Sep 25 | matures comfortably |
| Carrot | Half-hardy | — | Mar 2 – Mar 9 | May 1 – May 21 | Aug 16 – Sep 5 | matures comfortably |
| Broccoli | Half-hardy | Jan 26 – Feb 9 | Feb 23 – Mar 9 | Apr 19 – May 9 | Aug 21 – Sep 10 | matures comfortably |
Which crops fit this growing season
Using Lookingglass's own 237-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Lookingglass)
From NOAA's 1991–2020 Climate Normals at station USC00357331. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Apr 21 | May 9 | Oct 25 | Nov 17 | 188 |
| 32°F (freeze) | Mar 23 | Apr 16 | Nov 18 | Dec 17 | 237 |
| 28°F | Feb 20 | Mar 21 | Dec 11 | Jan 31 | 299 |
| 24°F | Jan 11 | Feb 26 | Dec 27 | Feb 15 | 362 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 29 locations is 1,858; Lookingglass's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,155 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 6,088 | cool-season crops (brassicas, greens) |
Hardiness zone 9a in Oregon
Zone 9a means an average annual extreme minimum winter temperature of about 20 to 25 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Oregon spans 9 hardiness zones in this dataset — see all Oregon locations for the full range, including zones5b, 6a, 6b, 7a, 7b, 8a, 8b, 9b.
Explore zone 9a in other states at zone 9a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 9a mean in Oregon?
- Zone 9a means an average annual extreme minimum winter temperature of 20 to 25 °F — the standard USDA measure of which perennials survive winter. 29 locations in Oregon fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Oregon's zone 9a is the growing season longest?
- Toledo runs the longest season on this page at about 306 days; Toledo is shortest at about 145 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Oregon's zone 9a?
- Using Lookingglass's frost dates (this page's median-season location): start seeds indoors about Jan 26 – Feb 9, then transplant outside about Mar 30 – Apr 6. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Oregon's zone 9a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 29 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.