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When to Plant Soybeans in Washington

Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.

Washington spans USDA hardiness zones 5b, 6a, 6b, 7a, 7b, 8a, 8b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

Find Your County

Click your county for exact Soybeans planting dates based on your local frost dates.

Hover over a county to see details. Click to view planting guide.

Soybeans Planting Calendar for Washington

Zone 5b ~178 day growing season · Full guide →

Last frost: April 18 · First frost: October 13 · 178 day season

Activity When Date Range
Direct Sow April 25 Apr 25 – May 16
Harvest July 18 Jul 18 – Sep 12
Zone 6a ~193 day growing season · Full guide →

Last frost: April 10 · First frost: October 20 · 193 day season

Activity When Date Range
Direct Sow April 17 Apr 17 – May 8
Harvest July 10 Jul 10 – Sep 4
Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

Activity When Date Range
Direct Sow April 10 Apr 10 – May 1
Harvest July 3 Jul 3 – Aug 28
Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity When Date Range
Direct Sow April 1 Apr 1 – Apr 22
Harvest June 24 Jun 24 – Aug 19
Zone 7b ~235 day growing season · Full guide →

Last frost: March 18 · First frost: November 8 · 235 day season

Activity When Date Range
Direct Sow March 25 Mar 25 – Apr 15
Harvest June 17 Jun 17 – Aug 12
Zone 8a ~255 day growing season · Full guide →

Last frost: March 8 · First frost: November 18 · 255 day season

Activity When Date Range
Direct Sow March 15 Mar 15 – Apr 5
Harvest June 7 Jun 7 – Aug 2
Zone 8b ~276 day growing season · Full guide →

Last frost: February 25 · First frost: November 28 · 276 day season

Activity When Date Range
Direct Sow March 4 Mar 4 – Mar 25
Harvest May 27 May 27 – Jul 22

Growing Tips for Washington

Direct sow after soil warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.

Frequently Asked Questions

When should I plant Soybeans in Washington?

Planting dates for Soybeans in Washington depend on your USDA zone. Washington spans zones 5b, 6a, 6b, 7a, 7b, 8a, 8b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Washington for planting?

Washington contains USDA hardiness zones 5b, 6a, 6b, 7a, 7b, 8a, 8b. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals, University Cooperative Extension planting guides. Last updated: April 2026.