Blog

When to Plant Thyme in Forest County, WI

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.

Forest County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 20 and the first fall frost is September 30, giving you a growing season of approximately 133 days.

At an elevation of 556 feet, Forest County receives approximately 34.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Thyme to ensure they mature before fall.

Forest County, WI (Zone 4a) Short season
133 days
Last Spring Frost May 20
133 growing days
First Fall Frost September 30

Forest County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 22 🍅 Harvest: Jul 31 – Oct 2
Recommended (50%) ✗ May not fit
Transplant: May 27 🍅 Harvest: Aug 5 – Oct 7
Safe Start (90%) ✗ May not fit
Transplant: Jun 7 🍅 Harvest: Aug 16 – Oct 18

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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~980 GDD — county provides 1,629 GDD Excellent fit

Thyme Planting Timeline โ€” Forest County, WI

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 27 May 27 โ€“ Jun 10
Harvest August 5 Aug 5 โ€“ Oct 7

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June Transplant Outdoors
July โ€”
August Harvest
September Harvest
October Harvest
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 4a

Growing Season

133 days

Growing Tips for Forest 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 Forest County, WI?

Forest County is in Zone 4a with an average last frost of May 20. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Forest County, WI?

Forest County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 20 and first fall frost is September 30.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Forest County gardeners in Zone 4a 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 Forest County, WI. Local conditions may vary. Last updated: April 2026.