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When to Plant Edamame in Mountrail County, ND

Mountrail County, North Dakota Zone 4a May

May in Mountrail County, North Dakota — your action list

A quick May briefing for Mountrail County, North Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 17
Avg. first frost September 22
Soil temp (4") 50°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Put edamame seeds straight in the ground

    These tolerate cool soil, so you're not gambling by sowing now.

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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.

Mountrail County, North Dakota is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 22, giving you a growing season of approximately 128 days.

At an elevation of 1,059 feet, Mountrail County receives approximately 26.2 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Edamame to ensure they mature before fall.

Mountrail County, ND (Zone 4a) Short season
128 days
Last Spring Frost May 17
128 growing days
First Fall Frost September 22

Mountrail County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (10 days to spare)
Transplant: May 12 🍅 Harvest: Jul 28 – Sep 8
Recommended (50%) ✓ Fits season (9 days to spare)
Transplant: May 17 🍅 Harvest: Aug 2 – Sep 13
Safe Start (90%) ✓ Fits season (11 days to spare)
Transplant: May 29 🍅 Harvest: Aug 14 – Sep 25

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 Mountrail County

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

Soil pH

Your soil pH (6.8–7.5) is more alkaline than Edamame prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Mountrail County is excellent for Edamame — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Edamame

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

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 55 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Edamame

Edamame needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Edamame Needs Rainfall You Supplement Action
Jan 2" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 3.9" 2.9" 1" 💧 Light watering
Jun 3.9" 1.7" 2.2" 🚿 Regular watering
Jul 3.9" 2.1" 1.8" 💧 Light watering
Aug 3.9" 2.7" 1.2" 💧 Light watering
Sep 3.9" 2.2" 1.7" 💧 Light watering
Oct 2.5" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Edamame 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.

Edamame needs ~744 GDD — county provides 1,088 GDD Excellent fit

Edamame Planting Timeline — Mountrail County, ND

Edamame Planting Calendar

Activity When Date Range
Direct Sow May 31 May 31 – Jun 21
Harvest August 16 Aug 16 – Sep 27

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
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Only during dry spells

📅 Days to Maturity

75–100 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4a

📆 Growing Season

128 days in Mountrail County

Growing Tips for Edamame in Mountrail County

Direct sow Edamame outdoors after May 17 in Mountrail County when soil has warmed and frost danger has passed.

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

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Edamame in Mountrail County, ND?

Mountrail County is in Zone 4a with an average last frost of May 17. Plan your Edamame planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mountrail County, ND?

Mountrail County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 22.

🌱

Your Mountrail County Garden Planner — Free

A 24-page printable planner built for Mountrail County (Zone 4a). 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 Mountrail County, ND. 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.