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When to plant Cosmos in Lawrence County, IL

Plant Cosmos in Lawrence County, when soil hits 50°F — usually April 13. Continue planting through May 4 for the spring crop.

When to Plant Cosmos in Lawrence County, IL

Lawrence County, Illinois Zone 6b June

Your June planting checklist for Lawrence County, Illinois

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Lawrence County, Illinois.

Avg. last frost April 13
Avg. first frost October 27
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
  1. Pick cosmos

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Looking ahead to 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.

Lawrence County, Illinois is in USDA Zone 6b. The average last spring frost is April 13 and the first fall frost is October 27, giving you a growing season of approximately 197 days.

At an elevation of 969 feet, Lawrence County receives approximately 35.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Cosmos during the growing season.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Lawrence County, IL (Zone 6b) Moderate season
197 days
Last Spring Frost April 13
197 growing days
First Fall Frost October 27

Lawrence County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.3

Drainage

Well Drained

Cosmos Planting Risk Windows

Early Start (70% safe) ✓ Fits season (18 days to spare)
Start indoors: Mar 10 Transplant: Apr 7 🌸 Bloom: Jun 16 – Sep 29
Recommended (50%) ✓ Fits season (22 days to spare)
Start indoors: Mar 16 Transplant: Apr 13 🌸 Bloom: Jun 22 – Oct 5
Safe Start (90%) ✓ Fits season (22 days to spare)
Start indoors: Mar 30 Transplant: Apr 27 🌸 Bloom: Jul 6 – Oct 19

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 Lawrence County

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

Soil pH

Your soil pH (5.8–7.3) overlaps with Cosmos's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Cosmos.

How to Plant Cosmos

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

Succession Planting Cosmos

3
successive plantings in your 197-day season

Sow every 6.9 weeks. Last sowing by Jul 29 to harvest before frost.

Cosmos Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/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 1.4" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 2.2" 3.3" 0" ✅ Rainfall sufficient
May 2.2" 4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.5" 0" ✅ Rainfall sufficient
Jul 2.2" 3.9" 0" ✅ Rainfall sufficient
Aug 2.2" 3.9" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 2.6" 0" ✅ Rainfall sufficient
Nov 2.5" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Lawrence 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 ~1,200 GDD — county provides 3,152 GDD Excellent fit

Cosmos Planting Timeline — Lawrence County, IL

Cosmos Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 – Mar 30
Transplant Outdoors April 13 Apr 13 – Apr 27
Direct Sow April 13 Apr 13 – May 4
Bloom June 22 Jun 22 – Oct 5

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Transplant Outdoors Direct Sow
May Direct Sow
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: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

197 days in Lawrence County

Growing Tips for Cosmos in Lawrence County

Direct sow Cosmos outdoors after April 13 in Lawrence 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 Lawrence County, IL?

Lawrence County is in Zone 6b with an average last frost of April 13. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lawrence County, IL?

Lawrence County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 13 and first fall frost is October 27.

When should I plant Cosmos in Lawrence County, IL?

In Lawrence County, IL, plant Cosmos after the last frost (around April 13) and before the first frost (around October 27). Best results when soil holds above 50°F.

What growing zone is Lawrence County, IL for Cosmos?

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

Can Cosmos grow in Lawrence County's climate?

Yes — Cosmos grows well in Lawrence County's temperate climate. Lawrence County averages a 197-day frost-free season, with last frost around April 13 and first frost around October 27.

🌱

Your Lawrence County Garden Planner — Free

A 22-page printable planner built for Lawrence County (Zone 6b). 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 Lawrence County, IL. 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.