When to Plant Edamame in Mills County, IA
May in the garden — Mills County, Iowa
Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.
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Outdoor sowing time: edamame
Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.
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.
Mills County, Iowa is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 7, giving you a growing season of approximately 164 days.
At an elevation of 1,355 feet, Mills County receives approximately 35.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Edamame during the growing season.
Mills County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.8
Drainage
Well Drained
Plant Planting Risk Windows
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 Mills County
How your county's soil matches Edamame's growing requirements.
Soil pH
Your soil pH (6.3–6.8) is within Edamame's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Mills County is excellent for Edamame — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Edamame.
Organic Matter
Organic matter is excellent (4.1%) — Edamame will thrive.
How to Plant Edamame
Succession Planting Edamame
Sow every 8.6 weeks. Last sowing by Jun 29 to harvest before frost.
Plant Water Budget
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 3.9" | 3" | 0.9" | 💧 Light watering |
| May | 3.9" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 3.9" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 3.9" | 4.2" | 0" | ✅ Rainfall sufficient |
| Aug | 3.9" | 3.5" | 0.4" | 💧 Light watering |
| Sep | 3.9" | 3.3" | 0.6" | 💧 Light watering |
| Oct | 3.9" | 2.6" | 1.3" | 💧 Light watering |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Mills 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 Planting Timeline — Mills County, IA
Edamame Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 3 | May 3 – May 24 |
| Harvest | July 19 | Jul 19 – Aug 30 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
164 days in Mills County
Growing Tips for Edamame in Mills County
Direct sow Edamame outdoors after April 26 in Mills 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
Check more plant combinations with our Companion Planting Checker →
Edamame in Other Locations
Frequently Asked Questions
When should I plant Edamame in Mills County, IA?
Mills County is in Zone 5b with an average last frost of April 26. Plan your Edamame planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mills County, IA?
Mills County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 7.
Your Mills County Garden Planner — Free
A 24-page printable planner built for Mills County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.