When to plant broccoli in Sunnyside, Grandview and Prosser, WA

Start broccoli from seed indoors Feb 13–27, then plant the young plants in the garden in Sunnyside, Grandview and Prosser Apr 3 – May 8. For a fall harvest, plant again Jul 14–28.

Moderate Plant young plants (starts)

Why these dates

Sunnyside, Grandview and Prosser's typical last spring frost is May 1. As a cool-season crop that handles light frost, this crop can go in about 4 weeks before that.

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
Spacing: 18 inches apart
Planting depth: Plant starts at the depth they grew in the pot
Frost: Handles light frost
First harvest: About 70 days after planting

Step by step

Start seeds indoors Feb 13–27 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 Apr 3 – May 8, 18 inches apart. Plant starts at the depth they grew in the pot.
Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
Plant again Jul 14–28 for a fall harvest.
Harvest: Cut the main head while the buds are tight and dark green. Side shoots follow for weeks.

Varieties that do well here

Packman
Green Magic
Purple Sprouting (overwinters west of the Cascades)

Watch out for

Cabbage worms and aphids. Cover young plants with insect netting.

Harvest the main head while buds are tight; side shoots follow for weeks.

Common questions

When is the last frost in Sunnyside, Grandview and Prosser, WA?

Typically May 1. In 9 years out of 10, frost is over by May 18. These are 1991–2020 NOAA climate normals for Sunnyside.

Is it too late to plant broccoli in Sunnyside, Grandview and Prosser?

The spring planting window runs through May 8. If you miss it, plant again for fall from July 14 to July 28.

When should I start broccoli from seed indoors in Sunnyside, Grandview and Prosser?

February 13 to February 27, which is 7 to 5 weeks before the April 3 planting date. Or buy young plants at a garden center instead.

Also plant in Sunnyside, Grandview and Prosser around the same time

Planting dates for broccoli in nearby areas

Yakima, WA Apr 10 – May 15
Tri-Cities (Pasco, Kennewick, Richland), WA Apr 1 – May 6
Walla Walla, WA Apr 1 – May 6
Moses Lake, WA Apr 1 – May 6
Ellensburg, WA Apr 15 – May 20
Ephrata and Quincy, WA Apr 1 – May 6

Full planting calendar for Sunnyside, Grandview and Prosser · Broccoli in every city