When to Plant Soybeans in Johnston County, OK
What to do in June
Here's what deserves your attention in Johnston County, Oklahoma this month. Everything below is tailored to Zone 8a and timed around your local frost dates.
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Bring in the soybeans
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
To set up a strong July, finish these tasks
- First harvests: soybeans
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.
Johnston County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 25 and the first fall frost is November 11, giving you a growing season of approximately 231 days.
At an elevation of 700 feet, Johnston County receives approximately 32.9 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Soybeans during the growing season.
Johnston County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.3
Drainage
Well Drained
Soybeans 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 Johnston County
How your county's soil matches Soybeans's growing requirements.
Soil pH
Your soil pH (6.3–7.3) overlaps with Soybeans's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Johnston County is excellent for Soybeans — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Soybeans will thrive.
How to Plant Soybeans
Succession Planting Soybeans
Sow every 9.1 weeks. Last sowing by Jul 14 to harvest before frost.
Soybeans 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 | — | 0.8" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | 4.3" | 2.3" | 2" | 💧 Light watering |
| Apr | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| May | 4.3" | 5.1" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 5.2" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Aug | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Sep | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Oct | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Nov | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Johnston 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 — Johnston County, OK
Soybeans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 1 | Apr 1 – Apr 22 |
| Harvest | June 24 | Jun 24 – Aug 19 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| 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 · 1-2 times/week
📅 Days to Maturity
80–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
231 days in Johnston County
Growing Tips for Soybeans in Johnston County
Direct sow Soybeans outdoors after March 25 in Johnston 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 Johnston County, OK?
Johnston County is in Zone 8a with an average last frost of March 25. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnston County, OK?
Johnston County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 25 and first fall frost is November 11.
Your Johnston County Garden Planner — Free
A 22-page printable planner built for Johnston County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.