GreenlyWhat to plant in December in the Pacific Northwest
Worked out for 11 cities from their own weather and frost dates, by zone.
What to sow and plant in December in the Pacific Northwest, by zone: frost possible, highs below 50 °F (Seattle, Portland and 9 more): garlic, broad bean, peas, spinach, radish and 3 more.
In the Pacific Northwest, December is winter.
Frost possible, highs below 50 °F: Seattle, Portland, Boise, Spokane and 7 more
In December, on average, these cities have highs of 34 to 48 °F and lows of 20 to 37 °F, 1.4 to 8.9 in of rain on 9 to 20 days; the day lasts 8 h 27 min to 9 h 06 min (on the 15th).
December falls in the frost season: frost-tender crops wait. Average first frost: Tacoma (December 3).
| How | What | Where |
|---|---|---|
| plant cloves | Garlic | Seattle, Portland, Boise and 6 more |
| start indoors, plant out in January or sow direct | Broad bean, spinach | Seattle, Portland, Salem and 4 more |
| sow direct | Peas, radish | Seattle, Portland, Salem and 3 more |
| plant sets | Onion | Salem, Eugene and Tacoma |
| start indoors, plant out in February or sow direct | Cabbage | Seattle, Portland, Boise and 6 more |
| start indoors, plant out in February | Broccoli | Seattle, Portland, Boise and 6 more |
| start indoors, plant out in February | Leek, parsley, Brussels sprouts | Salem and Eugene |
| start indoors, plant out in January | Kohlrabi | Salem and Eugene |
| plant bulbs | Crocus, daffodil, hyacinth, tulip | Seattle, Portland, Boise and 6 more |
Compared with November: new — leek, parsley, Brussels sprouts and kohlrabi; no longer sown — arugula and turnip.
Not starting in December: tomato (March, started indoors), bell pepper (March, started indoors), zucchini (April, started indoors), green beans (June, sown direct) and lettuce (February, started indoors) — dates for Portland.
Ready to harvest in December in Portland, if sown in the right month: broad bean (September), peas (October), spinach (October), lettuce (October), radish (November), Swiss chard (October), beet (October) and pumpkin (August).
How we work it out
For each city we use its average weather in December and the months after (highs, lows and rain for 2016–2025, ERA5 reanalysis via Open-Meteo) and its average frost dates. A crop starts in December if the month's mean temperature reaches the minimum soil temperature for germination on its card (we use the mean air temperature as a stand-in for the soil's) and if, over its first months (up to three), the average highs stay within its group's range, with no frost for crops that cannot take it. Crops started indoors count from the month they are planted out.
Temperature groups from Colorado State University Extension: cool-season crops prefer 60–80 °F and lose quality in heat; hardy ones grow in days as cool as 40 °F, semi-hardy ones from 40–50 °F (we use 50 °F); warm-season crops need days above 55 °F, and the most tender (tomato, pepper, eggplant, melon, watermelon, squash) above 60 °F, up to 95 °F. Crops the guide does not name go into the stricter group by their frost hardiness. Fava (broad) beans, which the guide does not name, count as hardy: hardy varieties are sown in fall and overwinter (RHS). Garlic and bulbs: a month before the first frost, and later only while the ground is not frozen (as on each city's page).
This is a general rule from averages: your garden can be a week or two earlier or later, and a greenhouse or a cold frame brings the season forward. Greenly works out the dates for your location.
- Moon planting calendar for December 2026
- What to plant in December: all climates
- Gardening in the United States: guide by region
Other months in the Pacific Northwest
- What to plant in December in the South
- What to plant in December in Texas
- What to plant in December in Florida
- What to plant in December in California
- What to plant in December in the Southwest
- What to plant in December in the Mountain West
- What to plant in December in the UK
- What to plant in December in Ireland
