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When to Plant Thyme in Milwaukee 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.

Milwaukee County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 27 and the first fall frost is October 11, giving you a growing season of approximately 167 days.

At an elevation of 1,100 feet, Milwaukee County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Thyme during the growing season.

Milwaukee County, WI (Zone 5b) Moderate season
167 days
Last Spring Frost April 27
167 growing days
First Fall Frost October 11

Milwaukee County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Transplant: Apr 29 🍅 Harvest: Jul 8 – Sep 9
Recommended (50%) ✓ Fits season (27 days to spare)
Transplant: May 4 🍅 Harvest: Jul 13 – Sep 14
Safe Start (90%) ✓ Fits season (25 days to spare)
Transplant: May 20 🍅 Harvest: Jul 29 – Sep 30

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~1,160 GDD — county provides 2,421 GDD Excellent fit

Thyme Planting Timeline โ€” Milwaukee County, WI

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 4 May 4 โ€“ May 18
Harvest July 13 Jul 13 โ€“ Sep 14

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 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

167 days

Growing Tips for Milwaukee 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 Milwaukee County, WI?

Milwaukee County is in Zone 5b with an average last frost of April 27. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Milwaukee County, WI?

Milwaukee County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 27 and first fall frost is October 11.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Milwaukee 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 Milwaukee County, WI. Local conditions may vary. Last updated: April 2026.