When to Plant Cosmos in Carter County, OK
Cosmos (Cosmos bipinnatus) is an airy, feathery-foliaged cottage garden annual from Mexico that thrives on neglect. It produces delicate daisy-like blooms in shades of pink, white, and magenta from midsummer until frost. Cosmos is a prolific self-sower — once established in a garden it often returns year after year without replanting. Excellent habitat plant for beneficial insects.
Carter County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 28 and the first fall frost is November 2, giving you a growing season of approximately 219 days.
At an elevation of 648 feet, Carter County receives approximately 34.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Cosmos during the growing season.
Carter County Soil Profile
Soil Type
Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Cosmos Planting Timeline — Carter County, OK
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 28 | Feb 28 – Mar 14 |
| Transplant Outdoors | March 14 | Mar 14 – Mar 28 |
| Direct Sow | March 14 | Mar 14 – Apr 4 |
| Bloom | May 23 | May 23 – Oct 10 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Transplant Outdoors Direct Sow |
| April | Direct Sow |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: N/A
🗺️ USDA Zone
Zone 8a
📆 Growing Season
219 days in Carter County
Growing Tips for Carter County
Direct-sow after last frost; cosmos germinates readily at 65-80°F in 7-10 days. Avoid rich soil — excess fertility produces lush foliage at the expense of blooms. Cosmos tolerates poor, dry soil exceptionally well. Pinch seedlings at 8 inches to encourage branching. Self-sows freely; allow some seed heads to mature and drop for a no-fuss perennial effect in warm climates.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Cosmos in Other Locations
Frequently Asked Questions
When should I plant Cosmos in Carter County, OK?
Carter County is in Zone 8a with an average last frost of March 28. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Carter County, OK?
Carter County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 28 and first fall frost is November 2.
Your Carter County Garden Planner — Free
A 22-page printable planner built for Carter 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.