When to Plant Edamame in Union County, SD
This month in Union County, South Dakota
Welcome to May in Zone 5a. These are the moves that will have the biggest impact on your growing season.
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Direct-sow edamame
These tolerate cool soil, so you're not gambling by sowing now.
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.
Union County, South Dakota is in USDA Zone 5a. The average last spring frost is April 30 and the first fall frost is October 5, giving you a growing season of approximately 158 days.
At an elevation of 938 feet, Union County receives approximately 22.8 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Edamame during the growing season.
Union County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
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 Union County
How your county's soil matches Edamame's growing requirements.
Soil pH
Your soil pH (6.8–7.2) overlaps with Edamame's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Union County is excellent for Edamame — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.3%). Annual compost additions will help Edamame.
How to Plant Edamame
Succession Planting Edamame
Sow every 8.6 weeks. Last sowing by Jun 27 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — 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 | — | 0.7" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | 3.9" | 2.8" | 1.1" | 💧 Light watering |
| May | 3.9" | 3.2" | 0.7" | 💧 Light watering |
| Jun | 3.9" | 3.7" | 0.2" | 💧 Light watering |
| Jul | 3.9" | 3.1" | 0.8" | 💧 Light watering |
| Aug | 3.9" | 2.4" | 1.5" | 💧 Light watering |
| Sep | 3.9" | 1.9" | 2" | 🚿 Regular watering |
| Oct | 3.9" | 1.5" | 2.4" | 🚿 Regular watering |
| Nov | — | 0.7" | 0" | ❄️ Dormant |
| Dec | — | 0.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Union 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 — Union County, SD
Edamame Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 7 | May 7 – May 28 |
| Harvest | July 23 | Jul 23 – Sep 3 |
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 | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · 1-2 times/week
📅 Days to Maturity
75–100 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
158 days in Union County
Growing Tips for Edamame in Union County
Direct sow Edamame outdoors after April 30 in Union 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.
Union County receives only 23" of rain annually. Edamame needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Union County, SD?
Union County is in Zone 5a with an average last frost of April 30. Plan your Edamame planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, SD?
Union County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is April 30 and first fall frost is October 5.
Your Union County Garden Planner — Free
A 24-page printable planner built for Union County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.