When to Plant Cosmos in Lake County, OH
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.
Lake County, Ohio is in USDA Zone 7a. The average last spring frost is May 5 and the first fall frost is October 13, giving you a growing season of approximately 161 days.
At an elevation of 740 feet, Lake County receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Cosmos during the growing season.
Lake County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Cosmos Planting Timeline — Lake County, OH
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 7 | Apr 7 – Apr 21 |
| Transplant Outdoors | May 5 | May 5 – May 19 |
| Direct Sow | May 5 | May 5 – May 26 |
| Bloom | July 14 | Jul 14 – Nov 3 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| 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 7a
📆 Growing Season
161 days in Lake County
Growing Tips for Lake 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 Lake County, OH?
Lake County is in Zone 7a with an average last frost of May 5. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lake County, OH?
Lake County, Ohio is in USDA Hardiness Zone 7a. The average last spring frost is May 5 and first fall frost is October 13.
Your Lake County Garden Planner — Free
A 22-page printable planner built for Lake County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.