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When to Plant Soybeans in Stevens County, WA

Stevens County, Washington Zone 6b May

May to-do list for Stevens County, Washington

Each item below is timed to Stevens County, Washington's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 10
Avg. first frost September 24
Soil temp (4") 54°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Direct-sow soybeans

    Your soil is 54°F — warm enough for these to germinate without babying.

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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.

Stevens County, Washington is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is September 24, giving you a growing season of approximately 137 days.

At an elevation of 1,751 feet, Stevens County receives approximately 24.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Soybeans to ensure they mature before fall.

Stevens County, WA (Zone 6b) Short season
137 days
Last Spring Frost May 10
137 growing days
First Fall Frost September 24

Stevens County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 2 🍅 Harvest: Jul 25 – Sep 19
Recommended (50%) ✗ May not fit
Transplant: May 10 🍅 Harvest: Aug 2 – Sep 27
Safe Start (90%) ✗ May not fit
Transplant: May 29 🍅 Harvest: Aug 21 – Oct 16

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Stevens County

How your county's soil matches Soybeans's growing requirements.

Soil pH

Your soil pH (5.3–6.3) is more acidic than Soybeans prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Stevens County is excellent for Soybeans — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.3%) — Soybeans will thrive.

How to Plant Soybeans

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 307 gal / 100 sq ft

Monthly Watering Guide for Soybeans

Soybeans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Soybeans Needs Rainfall You Supplement Action
Jan 3.2" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 1.3" 3" 🚿 Regular watering
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 0.3" 4" 🚿 Regular watering
Aug 4.3" 0.4" 3.9" 🚿 Regular watering
Sep 4.3" 0.9" 3.4" 🚿 Regular watering
Oct 2.3" 0" ❄️ Dormant
Nov 4.2" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Stevens County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Soybeans Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Soybeans needs ~1,225 GDD — county provides 1,678 GDD Excellent fit

Soybeans Planting Timeline — Stevens County, WA

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 17 May 17 – Jun 7
Harvest August 9 Aug 9 – Oct 4

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Direct Sow
June Direct Sow
July
August Harvest
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6b

📆 Growing Season

137 days in Stevens County

Growing Tips for Soybeans in Stevens County

Direct sow Soybeans outdoors after May 10 in Stevens County when soil has warmed and frost danger has passed.

Common pests for Soybeans in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

Stevens County receives only 24" of rain annually. Soybeans needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Soybeans in Stevens County, WA?

Stevens County is in Zone 6b with an average last frost of May 10. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Stevens County, WA?

Stevens County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is September 24.

🌱

Your Stevens County Garden Planner — Free

A 24-page printable planner built for Stevens County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Stevens County, WA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.