Regional guide

Walla Walla Inland Northwest Vegetable Garden

WSU Walla Walla County guide for Inland Northwest frost-free timing, microclimates, soils, sun, temperature, and watering.

Regional timing

Current regional planting plan

WSU Walla Walla County guide for Inland Northwest frost-free timing, microclimates, soils, sun, temperature, and watering.

Source-backed timing WSU Walla Walla Inland Northwest Vegetable Gardening

Walla Walla Inland NW 123 frost-free days

May 15 last frost spring release Sep 15 first frost fall limit

The WSU Walla Walla County Inland Northwest Climate and Soil section says the frost-free season is usually between May 15 and September 15.
The frost-free season varies from year to year, and the Inland Northwest has many microclimates.
Soil pH is generally neutral, ranging from 6.5 to 7.5, and soils can range from heavy clay loam to very sandy, sometimes in the same yard.

Catalog priority: 21 priority crops
Climate checks: 5 climate signals
Timing basis: Using Walla Walla Inland NW dates

Source-backed timing May 15 last frost and September 15 first frost from the Walla Walla Inland Northwest guide.

The frost-free season varies by year and across Inland Northwest microclimates.

Crop priority Provider Bush Bean leads the catalog examples

Provider Bush Bean, Detroit Dark Red Beet, Waltham 29 Broccoli, Long Island Improved Brussels Sprouts

Next local check Cool season vegetables can germinate in soil temperatures as low as 40F and mature during cool spring and early summer weather.

Broccoli, Brussels sprouts, and cabbage need to be started early indoors or purchased as transplants to mature before hot weather.

Calendar Convert regional timing into dated sowing, transplant, and harvest jobs. Frost dates Keep hardiness zone context separate from local first and last frost dates. All regions Compare this guide with the broader regional atlas. Western Washington WSU Extension guide for western Washington gardens where cool springs, rainfall, and mild winter microclimates shape vegetable planning.

Climate signals

The WSU Walla Walla County Inland Northwest Climate and Soil section says the frost-free season is usually between May 15 and September 15.
The frost-free season varies from year to year, and the Inland Northwest has many microclimates.
Soil pH is generally neutral, ranging from 6.5 to 7.5, and soils can range from heavy clay loam to very sandy, sometimes in the same yard.
Vegetables do best in full sun with a minimum of 6 hours, but leafy vegetables such as lettuce and spinach can grow in partial shade.
Morning sun only may be sufficient for beets and carrots, and good drainage is necessary.

Planning notes

Cool season vegetables can germinate in soil temperatures as low as 40F and mature during cool spring and early summer weather.
Broccoli, Brussels sprouts, and cabbage need to be started early indoors or purchased as transplants to mature before hot weather.
Warm season vegetables are damaged by frost, cold nights, and cold soil; they need warm soil of at least 60F and long warm days to mature.
Early varieties are best suited to the shorter gardening season of the Inland Northwest.
The WSU schedule says March 1 indoors: start cabbage, cauliflower, broccoli, Brussels sprouts, tomato, and pepper seeds; April 1 to 15 indoors: start tomato and eggplant seeds.
The April 15 to May 1 outdoor window includes beets, carrots, turnips, lettuce, spinach, chard, peas, radishes, potato pieces, and brassica transplants.
The May 15 to June 1 outdoor window includes beans and corn with a replant warning if frost occurs, plus cucumbers, melons, squash, tomatoes, peppers, and eggplant transplants.
The June 1 to June 15 outdoor window includes okra seeds, carrots, and tomatoes, peppers, and eggplant transplants.
Most vegetables need at least an inch of water a week, and hot and windy conditions can require additional watering.
Organic mulches should wait until the soil has warmed, about June 1, and young seedlings should not be mulched until they are six inches tall.
Do not plant the same crop or family of crops in the same place two years in a row.
Potatoes, onion sets, Jerusalem artichokes, asparagus crowns, and rhubarb roots are source rows without priority links; use priority catalog links as crop-row examples, not WSU cultivar recommendations.

Catalog crop examples

These catalog entries match crops covered by the regional timing source; variety-specific details remain tied to each seed entry's own source.

Provider Bush Bean Vegetable · Warm · 50 days
Detroit Dark Red Beet Vegetable · Cool · 58 days
Waltham 29 Broccoli Vegetable · Cool · 74 days
Long Island Improved Brussels Sprouts Vegetable · Cool · 100 days
Golden Acre Cabbage Vegetable · Cool · 64 days
Danvers 126 Carrot Vegetable · Shoulder · 70 days
Snowball Y Cauliflower Vegetable · Cool · 70 days
Bright Lights Swiss Chard Vegetable · Shoulder · 55 days
Golden Bantam Sweet Corn Vegetable · Warm · 80 days
Marketmore 76 Cucumber Vegetable · Warm · 58 days
Black Beauty Eggplant Vegetable · Warm · 80 days
Black Seeded Simpson Lettuce Vegetable · Cool · 45 days
Hale's Best Jumbo Melon Vegetable · Warm · 85 days
Clemson Spineless Okra Vegetable · Warm · 56 days
Sugar Snap Pea Vegetable · Cool · 62 days
California Wonder Pepper Vegetable · Warm · 72 days
French Breakfast Radish Vegetable · Cool · 28 days
Bloomsdale Spinach Vegetable · Cool · 42 days
Waltham Butternut Squash Vegetable · Warm · 95 days
Roma Tomato Vegetable · Warm · 76 days
Purple Top White Globe Turnip Vegetable · Cool · 55 days

Related regional guides

Washington West of the Cascades Vegetable Garden WSU Extension guide for western Washington gardens where cool springs, rainfall, and mild winter microclimates shape vegetable planning.

Source: WSU Walla Walla Inland Northwest Vegetable Gardening