When to Plant Soybeans in Jefferson County, AR
Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.
Jefferson County, Arkansas is in USDA Zone 7b. The average last spring frost is March 19 and the first fall frost is November 9, giving you a growing season of approximately 235 days.
At an elevation of 454 feet, Jefferson County receives approximately 51.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Soybeans during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Soybeans root diseases.
Jefferson County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-7.1
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 Jefferson County
How your county's soil matches Soybeans's growing requirements.
Soil pH
Your soil pH (5.3–7.1) overlaps with Soybeans's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Jefferson County is excellent for Soybeans — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Soybeans.
How to Plant Soybeans
Succession Planting Soybeans
Sow every 9.1 weeks. Last sowing by Jul 12 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Soybeans
Soybeans needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Soybeans Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4" | 0" | ❄️ Dormant |
| Feb | — | 3.9" | 0" | ❄️ Dormant |
| Mar | 4.3" | 5.4" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| May | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jun | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 5.5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 5.1" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Nov | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Jefferson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Soybeans 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.
Soybeans Planting Timeline — Jefferson County, AR
Soybeans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 26 | Mar 26 – Apr 16 |
| Harvest | June 18 | Jun 18 – Aug 13 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Direct Sow |
| April | Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
80–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7b
📆 Growing Season
235 days in Jefferson County
Growing Tips for Soybeans in Jefferson County
Direct sow Soybeans outdoors after March 19 in Jefferson County when soil has warmed and frost danger has passed.
Common pests for Soybeans 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 warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Soybeans in Other Locations
Frequently Asked Questions
When should I plant Soybeans in Jefferson County, AR?
Jefferson County is in Zone 7b with an average last frost of March 19. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jefferson County, AR?
Jefferson County, Arkansas is in USDA Hardiness Zone 7b. The average last spring frost is March 19 and first fall frost is November 9.
Plan Your Garden with Confidence
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