When to Plant Onion in Cimarron County, OK
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Cimarron County, Oklahoma is in USDA Zone 6b. The average last spring frost is April 19 and the first fall frost is October 18, giving you a growing season of approximately 182 days.
At an elevation of 1,132 feet, Cimarron County receives approximately 28.5 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Onion during the growing season.
Cimarron County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.4
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 Cimarron County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (6.5–7.4) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Cimarron County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Onion.
Organic Matter
Organic matter is moderate (3.5%). Annual compost additions will help Onion.
How to Plant Onion
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.7" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| May | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 5.1" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Aug | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Sep | 4.3" | 2.3" | 2" | 💧 Light watering |
| Oct | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Nov | — | 0.9" | 0" | ❄️ Dormant |
| Dec | — | 0.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Cimarron County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion 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.
Onion Planting Timeline — Cimarron County, OK
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 15 | Mar 15 – Mar 29 |
| Transplant Outdoors | April 19 | Apr 19 – May 3 |
| Direct Sow | April 5 | Apr 5 – Apr 26 |
| Harvest | July 19 | Jul 19 – Sep 6 |
| Fall Sowing | August 9 | Aug 9 – Aug 23 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 6b
📆 Growing Season
182 days in Cimarron County
Growing Tips for Onion in Cimarron County
Direct sow Onion outdoors after April 19 in Cimarron County when soil has warmed and frost danger has passed.
Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
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Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Cimarron County, OK?
Cimarron County is in Zone 6b with an average last frost of April 19. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cimarron County, OK?
Cimarron County, Oklahoma is in USDA Hardiness Zone 6b. The average last spring frost is April 19 and first fall frost is October 18.
Plan Your Garden with Confidence
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