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When to plant Cosmos in Gladwin County County,

The best window to plant Cosmos in Gladwin County County, is May 9–May 30, when soil warms to 50°F. Last frost typically hits May 9; first frost October 6.

When to Plant Cosmos in Gladwin County, MI

Gladwin County, Michigan Zone 6a June

Your June planting checklist for Gladwin County, Michigan

A quick June briefing for Gladwin County, Michigan gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 9
Avg. first frost October 6
Soil temp (4") 70°F
Watering Low
Pest pressure High
Daylight 15.3 hrs
  1. Begin indoor sowing: cosmos

    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

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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.

Gladwin County, Michigan is in USDA Zone 6a. The average last spring frost is May 9 and the first fall frost is October 6, giving you a growing season of approximately 150 days.

At an elevation of 832 feet, Gladwin County receives approximately 36.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Cosmos to ensure they mature before fall.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Gladwin County, MI (Zone 6a) Moderate season
150 days
Last Spring Frost May 9
150 growing days
First Fall Frost October 6
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Gladwin County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Cosmos Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 2 Transplant: Apr 30 🌸 Bloom: Jul 9 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: Apr 11 Transplant: May 9 🌸 Bloom: Jul 18 – Oct 24
Safe Start (90%) ✗ May not fit
Start indoors: Apr 22 Transplant: May 20 🌸 Bloom: Jul 29 – Nov 4

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 Gladwin County

How your county's soil matches Cosmos's growing requirements.

Soil pH

Your soil pH (6.2–7.3) is within Cosmos's preferred range (6.0–8.0).

Soil Texture

The silt loam soil in Gladwin County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.9%) — Cosmos will thrive.

How to Plant Cosmos

0.3"
Planting Depth
12"
Between Plants
18"
Between Rows

Succession Planting Cosmos

2
successive plantings in your 150-day season

Sow every 6.9 weeks. Last sowing by Jul 08 to harvest before frost.

Cosmos Water Budget

Plant needs
0.5″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.7" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 2.2" 4.4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.8" 0" ✅ Rainfall sufficient
Jul 2.2" 3.8" 0" ✅ Rainfall sufficient
Aug 2.2" 3.9" 0" ✅ Rainfall sufficient
Sep 2.2" 3.3" 0" ✅ Rainfall sufficient
Oct 2.2" 2.4" 0" ✅ Rainfall sufficient
Nov 2.6" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Gladwin 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 needs ~919 GDD — county provides 1,837 GDD Excellent fit

Cosmos Planting Timeline — Gladwin County, MI

Cosmos Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors May 9 May 9 – May 23
Direct Sow May 9 May 9 – May 30
Bloom July 18 Jul 18 – Oct 24

Plant 0.3" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June
July Bloom
August Bloom
September Bloom
October Bloom
November
December
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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 6a

📆 Growing Season

150 days in Gladwin County

Growing Tips for Cosmos in Gladwin County

Direct sow Cosmos outdoors after May 09 in Gladwin 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 →

Frequently Asked Questions

When should I plant Cosmos in Gladwin County, MI?

Gladwin County is in Zone 6a with an average last frost of May 9. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gladwin County, MI?

Gladwin County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is May 9 and first fall frost is October 6.

When should I plant Cosmos in Gladwin County County, ?

In Gladwin County County, , plant Cosmos after the last frost (around May 9) and before the first frost (around October 6). Best results when soil holds above 50°F.

What growing zone is Gladwin County County, for Cosmos?

Gladwin County County sits in USDA Zone 6a. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.

Can Cosmos grow in Gladwin County County's climate?

Yes — Cosmos grows well in Gladwin County County's temperate climate. Gladwin County County averages a 150-day frost-free season, with last frost around May 9 and first frost around October 6.

🌱

Your Gladwin County Garden Planner — Free

A 22-page printable planner built for Gladwin County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Gladwin County, MI. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.