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When to Plant Soybeans in Washington County, UT

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 County, Utah is in USDA Zone 8a. The average last spring frost is April 6 and the first fall frost is November 1, giving you a growing season of approximately 209 days.

At an elevation of 3,524 feet, Washington County receives approximately 12.7 inches of rainfall annually with predominantly loam soil. Summer highs average 90ยฐF, providing good warmth for Soybeans during the growing season. With low rainfall, drip irrigation is essential for growing Soybeans successfully. Mulch heavily to conserve soil moisture.

Washington County, UT (Zone 8a) Long season
209 days
Last Spring Frost April 6
209 growing days
First Fall Frost November 1

Washington County Soil Profile

Soil Type

Loam

Soil pH

6.7-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (77 days to spare)
Transplant: Mar 13 🍅 Harvest: Jun 5 – Jul 31
Recommended (50%) ✓ Fits season (69 days to spare)
Transplant: Apr 6 🍅 Harvest: Jun 29 – Aug 24
Safe Start (90%) ✓ Fits season (38 days to spare)
Transplant: May 27 🍅 Harvest: Aug 19 – Oct 14

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 2,332 gal / 100 sq ft
Drought risk

Water stress score is 10/10 โ€” consider drought-tolerant varieties and mulching

Soybeans needs ~1,750 GDD — county provides 3,657 GDD Excellent fit

Soybeans Planting Timeline โ€” Washington County, UT

Soybeans Planting Calendar

Activity When Date Range
Direct Sow April 13 Apr 13 โ€“ May 4
Harvest July 6 Jul 6 โ€“ Aug 31

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 8a

Growing Season

209 days

Growing Tips for Washington County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Soybeans in Washington County, UT?

Washington County is in Zone 8a with an average last frost of April 6. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Washington County, UT?

Washington County, Utah is in USDA Hardiness Zone 8a. The average last spring frost is April 6 and first fall frost is November 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Washington County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.

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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 Washington County, UT. Local conditions may vary. Last updated: April 2026.