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When to Plant Thyme in Audubon County, IA

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.

Audubon County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 3, giving you a growing season of approximately 158 days.

At an elevation of 1,056 feet, Audubon County receives approximately 32.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Thyme during the growing season.

Audubon County, IA (Zone 5a) Moderate season
158 days
Last Spring Frost April 28
158 growing days
First Fall Frost October 3

Audubon County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 9 – Sep 10
Recommended (50%) ✓ Fits season (18 days to spare)
Transplant: May 5 🍅 Harvest: Jul 14 – Sep 15
Safe Start (90%) ✓ Fits season (14 days to spare)
Transplant: May 21 🍅 Harvest: Jul 30 – Oct 1

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
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Thyme needs ~1,160 GDD — county provides 2,291 GDD Excellent fit

Thyme Planting Timeline โ€” Audubon County, IA

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 5 May 5 โ€“ May 19
Harvest July 14 Jul 14 โ€“ Sep 15

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 5a

Growing Season

158 days

Growing Tips for Audubon 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 Audubon County, IA?

Audubon County is in Zone 5a with an average last frost of April 28. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Audubon County, IA?

Audubon County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Audubon County gardeners in Zone 5a 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 Audubon County, IA. Local conditions may vary. Last updated: April 2026.