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.
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