When to plant Cosmos in Clark County, AR
Plant Cosmos in Clark County, when soil hits 50°F — usually March 8. Continue planting through March 29 for the spring crop.
When to Plant Cosmos in Clark County, AR
June to-do list for Clark County, Arkansas
Here's what deserves your attention in Clark County, Arkansas this month. Everything below is tailored to Zone 8a and timed around your local frost dates.
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Collect cosmos at their peak
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
To set up a strong July, finish these tasks
- First harvests: cosmos
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.
Clark County, Arkansas is in USDA Zone 8a. The average last spring frost is March 22 and the first fall frost is November 9, giving you a growing season of approximately 232 days.
At an elevation of 1,350 feet, Clark County receives approximately 45.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Cosmos during the growing season.
Clark County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.7
Drainage
Well Drained
Cosmos 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 Clark County
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (5.7–6.7) overlaps with Cosmos's range (6.0–8.0), though not a perfect match.
Soil Texture
The silt loam soil in Clark County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Cosmos prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Cosmos.
How to Plant Cosmos
Succession Planting Cosmos
Sow every 6.9 weeks. Last sowing by Aug 11 to harvest before frost.
Cosmos Water Budget
Monthly Watering Guide for Cosmos
Cosmos needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Cosmos Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4.2" | 0" | ❄️ Dormant |
| Feb | — | 3.6" | 0" | ❄️ Dormant |
| Mar | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 3.8" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 5.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.5" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Clark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Cosmos 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.
Cosmos Planting Timeline — Clark County, AR
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 22 | Feb 22 – Mar 8 |
| Transplant Outdoors | March 8 | Mar 8 – Mar 22 |
| Direct Sow | March 8 | Mar 8 – Mar 29 |
| Bloom | May 17 | May 17 – Oct 4 |
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
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
232 days in Clark County
Growing Tips for Cosmos in Clark County
Direct sow Cosmos outdoors after March 22 in Clark County when soil has warmed and frost danger has passed.
Common pests for Cosmos in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
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 Clark County, AR?
Clark County is in Zone 8a 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 Clark County, AR?
Clark County, Arkansas is in USDA Hardiness Zone 8a. The average last spring frost is March 22 and first fall frost is November 9.
When should I plant Cosmos in Clark County, AR?
In Clark County, AR, plant Cosmos after the last frost (around March 22) and before the first frost (around November 9). Best results when soil holds above 50°F.
What growing zone is Clark County, AR for Cosmos?
Clark County sits in USDA Zone 8a. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cosmos grow in Clark County's climate?
Yes — Cosmos grows well in Clark County's temperate climate. Clark County averages a 232-day frost-free season, with last frost around March 22 and first frost around November 9.
Your Clark County Garden Planner — Free
A 22-page printable planner built for Clark 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.