GreenlyWhat to plant in March in the Pacific Northwest
Worked out for 11 cities from their own weather and frost dates, by zone.
What to sow and plant in March in the Pacific Northwest, by zone: frost possible, highs of 50–61 °F (Seattle, Portland and 7 more): broad bean, peas, onion, spinach, lettuce and 27 more; frost possible, highs below 50 °F (Spokane and Idaho Falls): broad bean, peas, lettuce, radish, cauliflower and 15 more.
In the Pacific Northwest, March is spring.
Frost possible, highs of 50–61 °F: Seattle, Portland, Boise, Salem and 5 more
In March, on average, these cities have highs of 52 to 55 °F and lows of 31 to 38 °F, 1.2 to 7.2 in of rain on 8 to 19 days; the day lasts 11 h 50 min to 11 h 53 min (on the 15th).
March falls in the frost season: frost-tender crops wait. Average last frost: Seattle (March 20), Portland (March 26), Salem (March 27), Olympia (March 19) and Tacoma (March 15).
| How | What | Where |
|---|---|---|
| sow direct | Broad bean, peas, spinach, lettuce, radish, cabbage, Swiss chard, arugula, chamomile, daikon | all |
| plant sets | Onion, shallot | all |
| sow direct | Carrot, broccoli, dill, mustard greens | Seattle, Portland, Salem and 2 more |
| start indoors, plant out in April | Cauliflower | Seattle, Portland, Salem and 4 more |
| sow direct or start indoors, plant out in April | Beet | all |
| start indoors, plant out in May | Tomato, bell pepper, eggplant, chili pepper, Florence fennel, moringa | Seattle, Portland, Salem and 5 more |
| start indoors, plant out in May | Parsley | Seattle, Portland, Salem and 4 more |
| start indoors, plant out in June | Celeriac, celery, chayote | Seattle, Portland, Salem and 5 more |
| sow direct | Kale, parsnip, turnip | Seattle, Portland, Boise and 5 more |
| start indoors, plant out in April | Kohlrabi | Seattle, Portland, Boise and 5 more |
| start indoors, plant out in May | Brussels Sprouts | Seattle and Olympia |
Compared with February: new — carrot, tomato, bell pepper, eggplant, chili pepper, Florence fennel, moringa, dill and 1 more.
Not starting in March: zucchini (April, started indoors) and green beans (June, sown direct) — dates for Medford.
Ready to harvest in March in Medford, if sown in the right month: cabbage (November).
Frost possible, highs below 50 °F: Spokane and Idaho Falls
In March, on average, these cities have highs of 47 to 50 °F and lows of 26 to 30 °F, 1.6 to 2.2 in of rain on 10 to 12 days; the day lasts 11 h 50 min to 11 h 52 min (on the 15th).
March falls in the frost season: frost-tender crops wait.
| How | What | Where |
|---|---|---|
| start indoors, plant out in April | Broad bean, cauliflower | Spokane |
| sow direct | Peas, radish | Spokane |
| start indoors, plant out in April | Lettuce, Swiss chard, beet, arugula, chamomile, kohlrabi | all |
| start indoors, plant out in May | Tomato, bell pepper, eggplant, parsley, chili pepper, Florence fennel, moringa | Spokane |
| start indoors, plant out in June | Celeriac, celery, chayote | all |
Compared with February: new — peas, radish, cauliflower, Swiss chard, beet, tomato, bell pepper, eggplant and 5 more; no longer sown — spinach, cabbage and Brussels sprouts.
Not starting in March: zucchini (May, started indoors), green beans (June, sown direct) and spinach (September, started indoors) — dates for Idaho Falls.
How we work it out
For each city we use its average weather in March 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 March 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 March 2027
- What to plant in March: all climates
- Gardening in the United States: guide by region
Other months in the Pacific Northwest
- What to plant in March in the Northeast and Midwest
- What to plant in March in the South
- What to plant in March in Texas
- What to plant in March in Florida
- What to plant in March in California
- What to plant in March in the Southwest
- What to plant in March in the Mountain West
- What to plant in March in Canada
- What to plant in March in the UK
- What to plant in March in Ireland
