Blog

When to Plant Thyme in Madison County, MT

Madison County, Montana Zone 5a May

Madison County, Montana gardeners: here's your May plan

Your Madison County, Montana garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost June 11
Avg. first frost September 13
Soil temp (4") 35°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
A few tasks this May that'll pay off in June
  • Transplants going out: thyme

Instant PDF download. No spam, unsubscribe any time.

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.

Madison County, Montana is in USDA Zone 5a. The average last spring frost is June 11 and the first fall frost is September 13, giving you a growing season of approximately 94 days.

At an elevation of 6,394 feet, Madison County receives approximately 20.7 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Thyme to ensure they mature before fall.

Madison County, MT (Zone 5a) Very short season
94 days
Last Spring Frost June 11
94 growing days
First Fall Frost September 13

Madison County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Jun 10 🍅 Harvest: Aug 19 – Oct 21
Recommended (50%) ✗ May not fit
Transplant: Jun 18 🍅 Harvest: Aug 27 – Oct 29
Safe Start (90%) ✗ May not fit
Transplant: Jun 29 🍅 Harvest: Sep 7 – Nov 9

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 Madison County

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

Soil pH

Your soil pH (6.6–8.1) overlaps with Thyme's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Thyme.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Thyme.

How to Plant Thyme

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

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.5" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 2.3" 0" ❄️ Dormant
Jun 1.3" 1.4" 0" ✅ Rainfall sufficient
Jul 1.3" 1.7" 0" ✅ Rainfall sufficient
Aug 1.3" 2.2" 0" ✅ Rainfall sufficient
Sep 1.3" 1.8" 0" ✅ Rainfall sufficient
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Madison 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 940 GDD Good fit

Thyme Planting Timeline — Madison County, MT

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors June 18 Jun 18 – Jul 2
Harvest August 27 Aug 27 – Oct 29

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

Month-by-Month Timeline

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

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 5a

📆 Growing Season

94 days in Madison County

Growing Tips for Thyme in Madison County

Direct sow Thyme outdoors after June 11 in Madison County when soil has warmed and frost danger has passed.

Your 94.0-day growing season in Madison County is tight for Thyme (70.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Madison County, MT?

Madison County is in Zone 5a with an average last frost of June 11. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Madison County, MT?

Madison County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 11 and first fall frost is September 13.

🌱

Your Madison County Garden Planner — Free

A 24-page printable planner built for Madison County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Madison County, MT. Local conditions may vary. Last updated: May 2026.

Sources & credits

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