When to plant tomatoes in Walla Walla, WA

Start tomatoes from seed indoors Mar 6–20, then plant the young plants in the garden in Walla Walla May 1–29.

Moderate Plant young plants (starts)

Why these dates

Walla Walla's typical last spring frost is March 27. Frost kills tomatoes, and warm-season crops also need warm soil. Soil here stays cold for weeks after the last frost, so planting waits until about May 1.

Columbia Basin and low eastern valleys. Hot, dry summers and quick spring warm-up. Warm crops go in earlier than west of the Cascades, and irrigation matters more than rain.

Difficulty: Moderate
Sun: Full sun; the hottest spot you have
Spacing: 2 feet apart
Planting depth: Bury the stem up to the first leaves
Frost: Killed by frost
First harvest: About 75 days after planting

Step by step

Start seeds indoors Mar 6–20 in trays or small pots under a grow light or in your sunniest window. Or skip this step and buy young plants (starts) at a garden center.
Harden off the young plants: about a week before planting, set them outside for a few hours a day, a little longer each day.
Plant them in the garden May 1–29, 2 feet apart. Bury the stem up to the first leaves.
Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
Harvest: Pick when fully colored. Before fall rains, pick green tomatoes and ripen them indoors.

Varieties that do well here

Stupice
Early Girl
Sungold (cherry)
Oregon Spring (bred at OSU)

Watch out for

Late blight in wet falls turns leaves and fruit brown. Keep leaves dry and give plants space.

OSU Extension advises waiting for soil consistently above 70°F. Early or cherry varieties ripen most reliably here.

Common questions

When is the last frost in Walla Walla, WA?

Typically March 27. In 9 years out of 10, frost is over by April 22. These are 1991–2020 NOAA climate normals for Walla Walla Regional Airport.

Is it too late to plant tomatoes in Walla Walla?

The spring planting window runs through May 29. Later plantings may not have time to produce before the first fall frost, which usually arrives around October 31.

When should I start tomatoes from seed indoors in Walla Walla?

March 6 to March 20, which is 8 to 6 weeks before the May 1 planting date. Or buy young plants at a garden center instead.

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Also plant in Walla Walla around the same time

Planting dates for tomatoes in nearby areas

Pendleton, OR May 1–29
The Dalles, OR May 1–29
Yakima, WA May 8 – Jun 5
Wenatchee, WA May 1–29
Tri-Cities (Pasco, Kennewick, Richland), WA May 1–29
Moses Lake, WA May 1–29

Full planting calendar for Walla Walla · Tomatoes in every city