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When to Plant Edamame in Niobrara County, WY

Edamame are soybeans harvested at the immature green stage for a sweet, nutty snack. They are high in protein and easy to grow in warm climates.

Niobrara County, Wyoming is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 21, giving you a growing season of approximately 129 days.

At an elevation of 5,262 feet, Niobrara County receives approximately 19.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Edamame to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Edamame successfully. Mulch heavily to conserve soil moisture.

Niobrara County, WY (Zone 4b) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21

Niobrara County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Transplant: May 13 🍅 Harvest: Jul 29 – Sep 9
Recommended (50%) ✓ Fits season (10 days to spare)
Transplant: May 15 🍅 Harvest: Jul 31 – Sep 11
Safe Start (90%) ✓ Fits season (5 days to spare)
Transplant: Jun 4 🍅 Harvest: Aug 20 – Oct 1

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
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 503 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Edamame needs ~1,006 GDD — county provides 1,483 GDD Excellent fit

Edamame Planting Timeline โ€” Niobrara County, WY

Edamame Planting Calendar

Activity When Date Range
Direct Sow May 29 May 29 โ€“ Jun 19
Harvest August 14 Aug 14 โ€“ Sep 25

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

75โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

129 days

Growing Tips for Niobrara County

Direct sow after soil is warm. Do not over-fertilize with nitrogen. Harvest when pods are plump and bright green but before they start to yellow. Steam or boil pods before eating.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

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Frequently Asked Questions

When should I plant Edamame in Niobrara County, WY?

Niobrara County is in Zone 4b with an average last frost of May 15. Plan your Edamame planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Niobrara County, WY?

Niobrara County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

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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 Niobrara County, WY. Local conditions may vary. Last updated: April 2026.