When to plant Cosmos in Itasca County County,
Itasca County County sits in cold Zone 4a. Plant Cosmos May 17–June 7 for the single annual harvest; the October 1 first frost closes the window.
When to Plant Cosmos in Itasca County, MN
June in the garden — Itasca County, Minnesota
Each item below is timed to Itasca County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Start cosmos indoors
Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.
July will be here before you know it — start on
- 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.
Itasca County, Minnesota is in USDA Zone 4a. The average last spring frost is May 10 and the first fall frost is October 1, giving you a growing season of approximately 144 days.
At an elevation of 506 feet, Itasca County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Cosmos to ensure they mature before fall.
Itasca County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.3
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 Itasca County
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (6.0–7.3) is within Cosmos's preferred range (6.0–8.0).
Soil Texture
The silt loam soil in Itasca County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.2%) — Cosmos will thrive.
How to Plant Cosmos
Succession Planting Cosmos
Sow every 6.9 weeks. Last sowing by Jul 03 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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | — | 3.5" | 0" | ❄️ Dormant |
| May | 2.2" | 5" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.5" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Itasca 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 — Itasca County, MN
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 12 | Apr 12 – Apr 26 |
| Transplant Outdoors | May 17 | May 17 – May 31 |
| Direct Sow | May 17 | May 17 – Jun 7 |
| Bloom | July 26 | Jul 26 – 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 | Direct Sow |
| 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: ideal
🗺️ USDA Zone
Zone 4a
📆 Growing Season
144 days in Itasca County
Growing Tips for Cosmos in Itasca County
Direct sow Cosmos outdoors after May 10 in Itasca 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 Itasca County, MN?
Itasca County is in Zone 4a with an average last frost of May 10. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Itasca County, MN?
Itasca County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 10 and first fall frost is October 1.
When should I plant Cosmos in Itasca County County, ?
In Itasca County County, , plant Cosmos after the last frost (around May 10) and before the first frost (around October 1). Best results when soil holds above 50°F.
What growing zone is Itasca County County, for Cosmos?
Itasca County County sits in USDA Zone 4a. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cosmos grow in Itasca County County's climate?
Yes — Cosmos grows well in Itasca County County's temperate climate. Itasca County County averages a 144-day frost-free season, with last frost around May 10 and first frost around October 1.
Your Itasca County Garden Planner — Free
A 22-page printable planner built for Itasca County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.