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When to Plant Thyme in Tazewell 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.

Tazewell County, Illinois is in USDA Zone 5b. The average last spring frost is April 19 and the first fall frost is October 15, giving you a growing season of approximately 179 days.

At an elevation of 1,006 feet, Tazewell County receives approximately 40 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Thyme during the growing season.

Tazewell County, IL (Zone 5b) Moderate season
179 days
Last Spring Frost April 19
179 growing days
First Fall Frost October 15

Tazewell County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (38 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 30 – Sep 1
Recommended (50%) ✓ Fits season (39 days to spare)
Transplant: Apr 26 🍅 Harvest: Jul 5 – Sep 6
Safe Start (90%) ✓ Fits season (38 days to spare)
Transplant: May 10 🍅 Harvest: Jul 19 – Sep 20

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.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~1,220 GDD — county provides 2,729 GDD Excellent fit

Thyme Planting Timeline โ€” Tazewell County, IL

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 26 Apr 26 โ€“ May 10
Harvest July 5 Jul 5 โ€“ Sep 6

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 โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

70โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 5b

Growing Season

179 days

Growing Tips for Tazewell County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Thyme in Tazewell County, IL?

Tazewell County is in Zone 5b with an average last frost of April 19. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Tazewell County, IL?

Tazewell County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 19 and first fall frost is October 15.

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Plan Your Garden with Confidence

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

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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 Tazewell County, IL. Local conditions may vary. Last updated: April 2026.