When to plant Cosmos in Stearns County, MN
The best window to plant Cosmos in Stearns County, is May 10–May 31, when soil warms to 50°F. Last frost typically hits May 3; first frost October 6.
When to Plant Cosmos in Stearns County, MN
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.
Stearns County, Minnesota is in USDA Zone 4b. The average last spring frost is May 3 and the first fall frost is October 6, giving you a growing season of approximately 156 days.
At an elevation of 772 feet, Stearns County receives approximately 37.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Cosmos to ensure they mature before fall.
Stearns County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Cosmos Planting Timeline — Stearns County, MN
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 5 | Apr 5 – Apr 19 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | May 10 | May 10 – May 31 |
| Bloom | July 19 | Jul 19 – Oct 11 |
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 | — |
| 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 4b
📆 Growing Season
156 days in Stearns County
Growing Tips for Stearns 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 Stearns County, MN?
Stearns County is in Zone 4b with an average last frost of May 3. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Stearns County, MN?
Stearns County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is May 3 and first fall frost is October 6.
When should I plant Cosmos in Stearns County, MN?
In Stearns County, MN, plant Cosmos after the last frost (around May 3) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Stearns County, MN for Cosmos?
Stearns County sits in USDA Zone 4b. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cosmos grow in Stearns County's climate?
Yes — Cosmos grows well in Stearns County's temperate climate. Stearns County averages a 156-day frost-free season, with last frost around May 3 and first frost around October 6.
Your Stearns County Garden Planner — Free
A 22-page printable planner built for Stearns County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.