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When to Plant Thyme in Marinette 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.

Marinette County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 18 and the first fall frost is October 1, giving you a growing season of approximately 136 days.

At an elevation of 782 feet, Marinette County receives approximately 31.5 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.

Marinette County, WI (Zone 4b) Short season
136 days
Last Spring Frost May 18
136 growing days
First Fall Frost October 1

Marinette County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 18 🍅 Harvest: Jul 27 – Sep 28
Recommended (50%) ✗ May not fit
Transplant: May 25 🍅 Harvest: Aug 3 – Oct 5
Safe Start (90%) ✗ May not fit
Transplant: Jun 6 🍅 Harvest: Aug 15 – Oct 17

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 Marinette County

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

Soil pH

Your soil pH (5.8โ€“7.3) overlaps with Thyme's range (6.0โ€“8.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) โ€” Thyme will thrive.

How to Plant Thyme

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

Succession Planting Thyme

2
successive plantings in your 136-day season

Sow every 8 weeks. Last sowing by Jul 03 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
1.0″/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€” 1.1" 0" โ„๏ธ Dormant
Feb โ€” 1.2" 0" โ„๏ธ Dormant
Mar โ€” 2.4" 0" โ„๏ธ Dormant
Apr โ€” 3" 0" โ„๏ธ Dormant
May 1.3" 3.8" 0" โœ… Rainfall sufficient
Jun 1.3" 4.4" 0" โœ… Rainfall sufficient
Jul 1.3" 3.2" 0" โœ… Rainfall sufficient
Aug 1.3" 3.1" 0" โœ… Rainfall sufficient
Sep 1.3" 2.6" 0" โœ… Rainfall sufficient
Oct 1.3" 2.4" 0" โœ… Rainfall sufficient
Nov โ€” 2.4" 0" โ„๏ธ Dormant
Dec โ€” 1.8" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Oct in Marinette 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 ~980 GDD — county provides 1,666 GDD Excellent fit

Thyme Planting Timeline โ€” Marinette County, WI

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 25 May 25 โ€“ Jun 8
Harvest August 3 Aug 3 โ€“ Oct 5

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

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: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 4b

๐Ÿ“† Growing Season

136 days in Marinette County

Growing Tips for Thyme in Marinette County

Direct sow Thyme outdoors after May 18 in Marinette 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 Marinette County, WI?

Marinette County is in Zone 4b with an average last frost of May 18. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Marinette County, WI?

Marinette County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 18 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

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