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When to plant Cosmos in Colbert County County,

Colbert County County gardeners should plant Cosmos between March 23 and April 13 in spring. With Colbert County County's Zone 8a climate (last frost April 6), Cosmos needs 90 days to mature — plant by July 30 for a full harvest.

When to Plant Cosmos in Colbert County, AL

Colbert County, Alabama Zone 8a June

June in the garden — Colbert County, Alabama

June is a pivotal month for Colbert County, Alabama gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 6
Avg. first frost October 28
Soil temp (4") 80°F
Watering Low
Pest pressure High
Daylight 14.3 hrs
  1. Pick cosmos

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Get ahead of July
  • 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.

Colbert County, Alabama is in USDA Zone 8a. The average last spring frost is April 6 and the first fall frost is October 28, giving you a growing season of approximately 205 days.

At an elevation of 380 feet, Colbert County receives approximately 50.9 inches of rainfall annually with predominantly clay loam soil. Summer highs average 89°F, providing good warmth for Cosmos during the growing season. Clay soil retains moisture well for Cosmos, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cosmos root diseases.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Colbert County, AL (Zone 8a) Long season
205 days
Last Spring Frost April 6
205 growing days
First Fall Frost October 28

Colbert County Soil Profile

Soil Type

Clay Loam

Soil pH

5.5-6.2

Drainage

Well Drained

Cosmos Planting Risk Windows

Early Start (70% safe) ✓ Fits season (10 days to spare)
Start indoors: Feb 28 Transplant: Mar 14 🌸 Bloom: May 23 – Oct 10
Recommended (50%) ✓ Fits season (9 days to spare)
Start indoors: Mar 9 Transplant: Mar 23 🌸 Bloom: Jun 1 – Oct 19
Safe Start (90%) ✓ Fits season (17 days to spare)
Start indoors: Mar 21 Transplant: Apr 4 🌸 Bloom: Jun 13 – Oct 31

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 Colbert County

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

Soil pH

Your soil pH (5.5–6.2) is more acidic than Cosmos prefers (6.0–8.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Cosmos.

How to Plant Cosmos

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

Succession Planting Cosmos

4
successive plantings in your 205-day season

Sow every 6.9 weeks. Last sowing by Jul 30 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 4.2" 0" ❄️ Dormant
Feb 4.6" 0" ❄️ Dormant
Mar 4.8" 0" ❄️ Dormant
Apr 2.2" 3.6" 0" ✅ Rainfall sufficient
May 2.2" 3.5" 0" ✅ Rainfall sufficient
Jun 2.2" 5.1" 0" ✅ Rainfall sufficient
Jul 2.2" 5.1" 0" ✅ Rainfall sufficient
Aug 2.2" 4.4" 0" ✅ Rainfall sufficient
Sep 2.2" 3.6" 0" ✅ Rainfall sufficient
Oct 2.2" 3.7" 0" ✅ Rainfall sufficient
Nov 4.2" 0" ❄️ Dormant
Dec 4.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Colbert 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 ~1,256 GDD — county provides 3,433 GDD Excellent fit

Cosmos Planting Timeline — Colbert County, AL

Cosmos Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors March 23 Mar 23 – Apr 6
Direct Sow March 23 Mar 23 – Apr 13
Bloom June 1 Jun 1 – Oct 19

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors Transplant Outdoors Direct Sow
April Transplant Outdoors Direct Sow
May
June Bloom
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: too_acidic

🗺️ USDA Zone

Zone 8a

📆 Growing Season

205 days in Colbert County

Growing Tips for Cosmos in Colbert County

Direct sow Cosmos outdoors after April 06 in Colbert County when soil has warmed and frost danger has passed.

With Colbert County's clay soil (34% clay), work in 3-4 inches of compost before planting Cosmos. Avoid tilling when soil is wet to prevent compaction.

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 Colbert County, AL?

Colbert County is in Zone 8a with an average last frost of April 6. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.

What planting zone is Colbert County, AL?

Colbert County, Alabama is in USDA Hardiness Zone 8a. The average last spring frost is April 6 and first fall frost is October 28.

When should I plant Cosmos in Colbert County County, ?

In Colbert County County, , plant Cosmos after the last frost (around April 6) and before the first frost (around October 28). Best results when soil holds above 50°F.

What growing zone is Colbert County County, for Cosmos?

Colbert County County sits in USDA Zone 8a. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.

Can Cosmos grow in Colbert County County's climate?

Yes — Cosmos grows well in Colbert County County's temperate climate. Colbert County County averages a 205-day frost-free season, with last frost around April 6 and first frost around October 28.

🌱

Your Colbert County Garden Planner — Free

A 22-page printable planner built for Colbert County (Zone 8a). 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 Colbert County, AL. 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.