When to Plant Cosmos in Stettler, AB
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.
Stettler, Alberta is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 5, giving you a growing season of approximately 147 days.
At an elevation of 2,598 feet, Stettler receives approximately 18.3 inches of rainfall annually with predominantly dark brown chernozem soil. Summer highs average 74°F, so choose short-season varieties of Cosmos to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Cosmos successfully. Mulch heavily to conserve soil moisture.
Stettler Soil Profile
Soil Type
Dark Brown Chernozem
Soil pH
6.0-7.0
Drainage
Well Drained
Cosmos Planting Timeline — Stettler, AB
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 13 | Apr 13 – Apr 27 |
| Transplant Outdoors | May 18 | May 18 – Jun 1 |
| Direct Sow | May 18 | May 18 – Jun 8 |
| Bloom | July 27 | Jul 27 – Oct 19 |
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 | Transplant Outdoors Direct Sow |
| 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
147 days in Stettler
Growing Tips for Stettler
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 Stettler, AB?
Stettler is in Zone 4b with an average last frost of May 11. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Stettler, AB?
Stettler, Alberta is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 5.
Your Stettler Garden Planner — Free
A 22-page printable planner built for Stettler (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.