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When to Plant Thyme in Dunn County, ND

Dunn County, North Dakota Zone 4a May

Your May gardening checklist

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 14
Avg. first frost September 23
Soil temp (4") 53°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Plant out thyme

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

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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.

Dunn County, North Dakota is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 23, giving you a growing season of approximately 132 days.

At an elevation of 944 feet, Dunn County receives approximately 22.3 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.

Dunn County, ND (Zone 4a) Short season
132 days
Last Spring Frost May 14
132 growing days
First Fall Frost September 23
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Dunn County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 17 🍅 Harvest: Jul 26 – Sep 27
Recommended (50%) ✗ May not fit
Transplant: May 21 🍅 Harvest: Jul 30 – Oct 1
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 Dunn County

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

Soil pH

Your soil pH (6.2–7.5) is within Thyme's preferred range (6.0–8.0).

Soil Texture

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

Drainage

Drainage is adequate for Thyme.

Organic Matter

Organic matter is excellent (4.2%) — 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 132-day season

Sow every 8 weeks. Last sowing by Jun 25 to harvest before frost.

Plant Water Budget

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

Water stress score is 8/10 — 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 1.3" 2.5" 0" ✅ Rainfall sufficient
Jun 1.3" 1.5" 0" ✅ Rainfall sufficient
Jul 1.3" 1.9" 0" ✅ Rainfall sufficient
Aug 1.3" 2.6" 0" ✅ Rainfall sufficient
Sep 1.3" 1.9" 0" ✅ Rainfall sufficient
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Dunn 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 1,320 GDD Excellent fit

Thyme Planting Timeline — Dunn County, ND

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 21 May 21 – Jun 4
Harvest July 30 Jul 30 – Oct 1

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 Harvest
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: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

132 days in Dunn County

Growing Tips for Thyme in Dunn County

Direct sow Thyme outdoors after May 14 in Dunn 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 Dunn County, ND?

Dunn County is in Zone 4a with an average last frost of May 14. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dunn County, ND?

Dunn County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 23.

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Your Dunn County Garden Planner — Free

A 24-page printable planner built for Dunn 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 Dunn County, ND. 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.