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When to plant Thyme in Cass County County,

Cass County County's 139-day season only supports one Thyme planting per year. Sow between May 19 and June 2 for the best chance at full maturity before September 28.

When to Plant Thyme in Cass County, MN

Thyme
Cass County, Minnesota Zone 4a June

Your June planting checklist for Cass County, Minnesota

Your garden in Cass County, Minnesota is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 12
Avg. first frost September 28
Soil temp (4") 61°F
Watering Low
Pest pressure Moderate
Daylight 15.7 hrs
Coming up in July — start thinking about
  • First harvests: thyme

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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.

Cass County, Minnesota is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is September 28, giving you a growing season of approximately 139 days.

At an elevation of 938 feet, Cass County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Thyme to ensure they mature before fall.

Cass County, MN (Zone 4a) Short season
139 days
Last Spring Frost May 12
139 growing days
First Fall Frost September 28
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Cass County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.9

Drainage

Well Drained

Thyme Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 15 🍅 Harvest: Jul 24 – Sep 25
Recommended (50%) ✗ May not fit
Transplant: May 19 🍅 Harvest: Jul 28 – Sep 29
Safe Start (90%) ✗ May not fit
Transplant: Jun 3 🍅 Harvest: Aug 12 – Oct 14

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 Cass County

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

Soil pH

Your soil pH (5.9–6.9) overlaps with Thyme's range (6.0–8.0), though not a perfect match.

Soil Texture

The silt loam soil in Cass County is excellent for Thyme — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.6%) — 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 139-day season

Sow every 8 weeks. Last sowing by Jun 30 to harvest before frost.

Thyme 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 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 1.3" 3.5" 0" ✅ Rainfall sufficient
Jun 1.3" 3.9" 0" ✅ Rainfall sufficient
Jul 1.3" 3.8" 0" ✅ Rainfall sufficient
Aug 1.3" 3.5" 0" ✅ Rainfall sufficient
Sep 1.3" 3.2" 0" ✅ Rainfall sufficient
Oct 2.5" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Cass County). Supplement amounts are based on average rainfall — 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" — every day above 50°F 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 ~800 GDD — county provides 1,390 GDD Excellent fit

Thyme Planting Timeline — Cass County, MN

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 19 May 19 – Jun 2
Harvest July 28 Jul 28 – Sep 29

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June Transplant Outdoors
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

139 days in Cass County

Growing Tips for Thyme in Cass County

Direct sow Thyme outdoors after May 12 in Cass 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 Cass County, MN?

Cass County is in Zone 4a with an average last frost of May 12. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cass County, MN?

Cass County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is September 28.

When should I plant Thyme in Cass County County, ?

In Cass County County, , plant Thyme after the last frost (around May 12) and before the first frost (around September 28). Best results when soil holds above 50°F.

What growing zone is Cass County County, for Thyme?

Cass County County sits in USDA Zone 4a. Thyme grows reliably in zones 4a through 9b, so it's a good fit here.

Can Thyme grow in Cass County County's climate?

Yes — Thyme grows well in Cass County County's temperate climate. Cass County County averages a 139-day frost-free season, with last frost around May 12 and first frost around September 28.

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Your Cass County Garden Planner — Free

A 22-page printable planner built for Cass County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Cass County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.