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Regional Calendars, Climate & DataPacific Northwest Planting Calendar
The Cascades split the Pacific Northwest into two growing regions: cool, wet soil in spring on the west side, and cold winters, dry summers and irrigation on the east.
Key points
- Start by deciding whether you are west or east of the Cascades.
- West side: wait for soil to drain and warm, and plan fall crops.
- East side: plan irrigation and frost protection together.
- Keep notes to tune dates to your microclimate.
How do the Cascades split the calendar?
West of the Cascades, the climate is mild and maritime, with cool wet springs, dry summers and a long, gentle season for cool crops. East of the mountains, the climate is drier with colder winters, hotter summers and a heavier reliance on irrigation.
That means planting advice that fits a Willamette Valley garden will not fit a farm in the Columbia Basin or the high desert. Start with your side of the mountains and your own elevation, then refine with local extension guidance.
What do cool wet springs mean for planting?
West-side soils can stay cold and saturated into late spring. Seeds of warm-season crops often rot or stall in such soil. Waiting for the soil to drain and warm usually beats forcing an early planting, and raised beds, black plastic or low tunnels can speed warming where needed.
Cool-season crops such as peas, greens, brassicas, potatoes and onions suit the region well. Many growers also plant for fall and winter harvest because the mild climate supports cool crops far into the year.
- Raised beds drain and warm earlier
- Plastic mulch warms the soil
- Row cover helps with cold nights and wind
How do dry summers affect your plan?
Summers are dry across much of the region, so water supply becomes the main limiter for many crops. On the west side, gardens and vegetable farms often irrigate from midsummer on. On the east side, irrigation is needed throughout the season.
Plan irrigation systems before planting, mulch to hold soil moisture, and follow local water rules, which vary by district and can tighten in drought years. Drip irrigation limits wasted water and keeps foliage dry.
When do warm-season crops make sense?
Tomatoes, peppers, squash, melons and corn can be grown in much of the region, but cool nights and late warm-up call for careful variety choice and, often, transplants and season extension. Choose varieties known to do well in cool climates and check days to maturity against your frost-free window.
On the east side, hot summers favor warm-season crops once frost danger passes, but spring frost can still strike late. Keep protection on hand through your average last frost date plus a safety margin.
How do you plan for fall and winter crops?
Because fall arrives mild and wet on the west side, planning fall and winter crops is a big part of the calendar. Count back from your average first fall frost and, for overwintered crops, from the point where growth stops as days shorten. Late summer sowings of kale, carrots, beets and some greens often fit this window.
Day length is the hidden limiter. In late fall and winter, plants grow slowly or not at all because of short days, so harvest what you plant before then. Ask your extension office for crop-specific timing tied to your area.
How do you assemble your own Pacific Northwest calendar?
For example, if your last spring frost usually falls in mid-April on the west side, you might sow peas and greens before then when soil allows, hold warm-season transplants until nights warm, and start fall crops in mid to late summer. This illustrates the method and is not a date recommendation for your site.
Keep notes on soil condition, planting, emergence and weather. A short record each year helps you tune dates to your own microclimate, whether you farm near the coast, in a valley, or on the dry side of the mountains.
What mistakes cost Pacific Northwest growers the most?
The most frequent mistake on the west side is planting warm-season crops into cold, wet soil and watching them stall. On the east side it is underestimating frost risk after a warm spell. In both areas, late sowing of fall crops is common: by the time sowing happens, day length is too short for growth.
Another mistake is overlooking slug pressure and disease in cool, wet conditions. Spacing, clean beds and good drainage help, and any control product must follow the label and protect pollinators and other wildlife. Ask extension for current guidance.
Growers on both sides of the Cascades also face wildfire smoke and heat dome events in some summers. Keep shade cloth and extra irrigation capacity available, and watch for agency updates. Smoke can reduce light and heat can stop fruit set, so protect plants and harvest crews alike.
- Wait for soil to drain and warm
- Sow fall crops while days are still long
- Space plants for airflow in wet weather
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.