When to Plant Edamame in Walla Walla County, WA
May to-do list for Walla Walla County, Washington
A quick May briefing for Walla Walla County, Washington gardeners — what's urgent, what's next, and what can wait.
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.
Walla Walla County, Washington is in USDA Zone 7a. The average last spring frost is April 20 and the first fall frost is October 15, giving you a growing season of approximately 178 days.
At an elevation of 3,151 feet, Walla Walla County receives approximately 23.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Edamame during the growing season.
Walla Walla County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.4
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 Walla Walla County
How your county's soil matches Edamame's growing requirements.
Soil pH
Your soil pH (5.2–6.4) is more acidic than Edamame prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Walla Walla County is excellent for Edamame — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Edamame will thrive.
How to Plant Edamame
Succession Planting Edamame
Sow every 8.6 weeks. Last sowing by Jul 07 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 | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 2.7" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 3.9" | 1.7" | 2.2" | 🚿 Regular watering |
| May | 3.9" | 1.5" | 2.4" | 🚿 Regular watering |
| Jun | 3.9" | 1" | 2.9" | 🚿 Regular watering |
| Jul | 3.9" | 0.4" | 3.5" | 🚿 Regular watering |
| Aug | 3.9" | 0.5" | 3.4" | 🚿 Regular watering |
| Sep | 3.9" | 0.9" | 3" | 🚿 Regular watering |
| Oct | 3.9" | 2.2" | 1.7" | 💧 Light watering |
| Nov | — | 3.7" | 0" | ❄️ Dormant |
| Dec | — | 3.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Walla Walla 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 — Walla Walla County, WA
Edamame Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 27 | Apr 27 – May 18 |
| Harvest | July 13 | Jul 13 – Aug 24 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| 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: too_acidic
🗺️ USDA Zone
Zone 7a
📆 Growing Season
178 days in Walla Walla County
Growing Tips for Edamame in Walla Walla County
Direct sow Edamame outdoors after April 20 in Walla Walla 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.
Walla Walla County receives only 24" 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 Walla Walla County, WA?
Walla Walla County is in Zone 7a with an average last frost of April 20. Plan your Edamame planting based on this frost date — see the calendar above for exact timing.
What planting zone is Walla Walla County, WA?
Walla Walla County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is April 20 and first fall frost is October 15.
Your Walla Walla County Garden Planner — Free
A 24-page printable planner built for Walla Walla County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.