When to plant Cosmos in Union County, AR
Plant Cosmos in Union County from March 1 to March 22 in spring. Union County sits in USDA Zone 8b, with last frost around March 22 and first frost on November 3.
When to Plant Cosmos in Union County, AR
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.
Union County, Arkansas is in USDA Zone 8b. The average last spring frost is March 22 and the first fall frost is November 3, giving you a growing season of approximately 226 days.
At an elevation of 508 feet, Union County receives approximately 52 inches of rainfall annually with predominantly silt loam soil. Summer highs average 92°F, providing good warmth for Cosmos during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cosmos root diseases.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Cosmos Planting Timeline — Union County, AR
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 22 | Feb 22 – Mar 8 |
| Transplant Outdoors | March 1 | Mar 1 – Mar 15 |
| Direct Sow | March 1 | Mar 1 – Mar 22 |
| Bloom | May 10 | May 10 – Oct 11 |
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 | — |
| 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 8b
📆 Growing Season
226 days in Union County
Growing Tips for Union 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 Union County, AR?
Union County is in Zone 8b with an average last frost of March 22. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, AR?
Union County, Arkansas is in USDA Hardiness Zone 8b. The average last spring frost is March 22 and first fall frost is November 3.
When should I plant Cosmos in Union County, AR?
In Union County, AR, plant Cosmos after the last frost (around March 22) and before the first frost (around November 3). Best results when soil holds above 50°F.
What growing zone is Union County, AR for Cosmos?
Union County sits in USDA Zone 8b. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cosmos grow in Union County's climate?
Yes — Cosmos grows well in Union County's temperate climate. Union County averages a 226-day frost-free season, with last frost around March 22 and first frost around November 3.
Your Union County Garden Planner — Free
A 22-page printable planner built for Union County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.