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When to Plant Thyme in Macon County, IL

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.

Macon County, Illinois is in USDA Zone 5b. The average last spring frost is April 13 and the first fall frost is October 19, giving you a growing season of approximately 189 days.

At an elevation of 1,064 feet, Macon County receives approximately 31.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Thyme during the growing season.

Macon County, IL (Zone 5b) Moderate season
189 days
Last Spring Frost April 13
189 growing days
First Fall Frost October 19

Macon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Transplant: Apr 14 🍅 Harvest: Jun 23 – Aug 25
Recommended (50%) ✓ Fits season (49 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 29 – Aug 31
Safe Start (90%) ✓ Fits season (52 days to spare)
Transplant: May 1 🍅 Harvest: Jul 10 – Sep 11

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 Macon County

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

Soil pH

Your soil pH (6.0โ€“7.1) is within Thyme's preferred range (6.0โ€“8.0).

Soil Texture

The silt loam soil in Macon County is excellent for Thyme โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.3%) โ€” 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 189-day season

Sow every 8 weeks. Last sowing by Jul 21 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 โ€” 1.3" 0" โ„๏ธ Dormant
Feb โ€” 1.5" 0" โ„๏ธ Dormant
Mar โ€” 2.2" 0" โ„๏ธ Dormant
Apr 1.3" 2.9" 0" โœ… Rainfall sufficient
May 1.3" 3.1" 0" โœ… Rainfall sufficient
Jun 1.3" 4.1" 0" โœ… Rainfall sufficient
Jul 1.3" 3.5" 0" โœ… Rainfall sufficient
Aug 1.3" 3.5" 0" โœ… Rainfall sufficient
Sep 1.3" 2.9" 0" โœ… Rainfall sufficient
Oct 1.3" 2.3" 0" โœ… Rainfall sufficient
Nov โ€” 2.4" 0" โ„๏ธ Dormant
Dec โ€” 1.6" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Macon County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 ~1,160 GDD — county provides 2,740 GDD Excellent fit

Thyme Planting Timeline โ€” Macon County, IL

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 20 Apr 20 โ€“ May 4
Harvest June 29 Jun 29 โ€“ Aug 31

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June Harvest
July Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.3"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

70โ€“90 days

๐Ÿงช Soil pH

Needs 6โ€“8 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 5b

๐Ÿ“† Growing Season

189 days in Macon County

Growing Tips for Thyme in Macon County

Direct sow Thyme outdoors after April 13 in Macon 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 →

Frequently Asked Questions

When should I plant Thyme in Macon County, IL?

Macon County is in Zone 5b with an average last frost of April 13. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Macon County, IL?

Macon County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 13 and first fall frost is October 19.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Macon County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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