When to Plant Soybeans in Harper County, OK
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.
Harper County, Oklahoma is in USDA Zone 6b. The average last spring frost is April 15 and the first fall frost is October 18, giving you a growing season of approximately 186 days.
At an elevation of 861 feet, Harper County receives approximately 21.5 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Soybeans during the growing season.
Harper County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.2
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.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Soybeans Planting Timeline — Harper County, OK
Soybeans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 22 | Apr 22 – May 13 |
| Harvest | July 15 | Jul 15 – Sep 9 |
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 | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
80–120 days
Soil pH
6 – 7
USDA Zone
Zone 6b
Growing Season
186 days
Growing Tips for Harper County
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
Level Up Your Garden
Soybeans in Other Locations
Frequently Asked Questions
When should I plant Soybeans in Harper County, OK?
Harper County is in Zone 6b with an average last frost of April 15. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harper County, OK?
Harper County, Oklahoma is in USDA Hardiness Zone 6b. The average last spring frost is April 15 and first fall frost is October 18.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Harper County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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