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When to plant Thyme in Casey,

In Casey, Thyme is a single-season spring crop — there's no second fall window. Plant April 21–May 5 for an 90-day harvest, finishing well before the October 17 first frost.

When to Plant Thyme in Casey, IL

Thyme
Casey, IL Zone 6b June

June in Casey, IL — your action list

Welcome to June in Zone 6b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 14
Avg. first frost October 17
Soil temp (4") 75°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Basket week: thyme

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

A few tasks this June that'll pay off in July
  • First harvests: thyme

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Thyme is a low-growing perennial herb with tiny, aromatic leaves and a warm, earthy flavor. It is one of the most versatile culinary and medicinal herbs.

Casey, Illinois is in USDA Zone 6b. The average last spring frost is April 14 and the first fall frost is October 17, giving you a growing season of approximately 186 days.

At an elevation of 591 feet, Clark County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Thyme during the growing season.

Casey, IL (Zone 6b) Moderate season
186 days
Last Spring Frost April 14
186 growing days
First Fall Frost October 17
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Casey Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Thyme Planting Risk Windows

Early Start (70% safe) ✓ Fits season (46 days to spare)
Transplant: Apr 16 🍅 Harvest: Jun 25 – Aug 27
Recommended (50%) ✓ Fits season (46 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 30 – Sep 1
Safe Start (90%) ✓ Fits season (46 days to spare)
Transplant: May 5 🍅 Harvest: Jul 14 – Sep 15

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 Casey

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

Soil pH

Your soil pH (6.2–6.8) is within Thyme's preferred range (6.0–8.0).

Soil Texture

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

Organic Matter

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

How to Plant Thyme

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Thyme

3
successive plantings in your 186-day season

Sow every 8 weeks. Last sowing by Jul 19 to harvest before frost.

Thyme Water Budget

Plant needs
0.3″/week
Rainfall provides
0.9″/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 Thyme

Thyme needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Thyme Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 1.3" 4.3" 0" ✅ Rainfall sufficient
May 1.3" 4.5" 0" ✅ Rainfall sufficient
Jun 1.3" 5.4" 0" ✅ Rainfall sufficient
Jul 1.3" 4.1" 0" ✅ Rainfall sufficient
Aug 1.3" 4.7" 0" ✅ Rainfall sufficient
Sep 1.3" 4" 0" ✅ Rainfall sufficient
Oct 1.3" 3.6" 0" ✅ Rainfall sufficient
Nov 2.5" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Clark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Thyme 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.

Thyme needs ~1,400 GDD — county provides 3,255 GDD Excellent fit

Thyme Planting Timeline — Casey, IL

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 21 Apr 21 – May 5
Harvest June 30 Jun 30 – Sep 1

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May Transplant Outdoors
June Harvest
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

186 days in Clark County

Growing Tips for Thyme in Casey

Direct sow Thyme outdoors after April 14 in Clark County when soil has warmed and frost danger has passed.

General growing tips

Start from seed, cuttings, or divisions. Plant in well-drained, lean soil. Prune lightly after flowering. Replace plants every 3-4 years when they become woody.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

When should I plant Thyme in Casey, ?

In Casey, , plant Thyme after the last frost (around April 14) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Casey, for Thyme?

Casey sits in USDA Zone 6b. Thyme grows reliably in zones 4a through 9b, so it's a good fit here.

Can Thyme grow in Casey's climate?

Yes — Thyme grows well in Casey's temperate climate. Casey averages a 186-day frost-free season, with last frost around April 14 and first frost around October 17.

🌱

Your Clark County Garden Planner — Free

A 22-page printable planner built for Clark 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 Clark County, IL. Local conditions may vary. Last updated: June 2026.