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When to plant Lemon Thyme in Mills County, IA

Plant Lemon Thyme in Mills County, between May 3 and May 17 — the only viable window. Zone 5b's short season (164 frost-free days) rules out a fall crop.

When to Plant Lemon Thyme in Mills County, IA

Lemon thyme is a low-growing perennial herb with tiny, citrus-scented leaves. It combines the savory quality of thyme with a bright lemon flavor, excellent with fish and poultry.

Mills County, Iowa is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 7, giving you a growing season of approximately 164 days.

At an elevation of 1,355 feet, Mills County receives approximately 35.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Lemon Thyme during the growing season.

Mills County, IA (Zone 5b) Moderate season
164 days
Last Spring Frost April 26
164 growing days
First Fall Frost October 7

Mills County Soil Profile

Soil Type

Silt Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Lemon Thyme Planting Timeline — Mills County, IA

Lemon Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 3 May 3 – May 17
Harvest July 12 Jul 12 – Sep 13

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Low — drought tolerant

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: N/A

🗺️ USDA Zone

Zone 5b

📆 Growing Season

164 days in Mills County

Growing Tips for Mills County

Start from cuttings or divisions. Plant in well-drained soil. Trim back after flowering. Use as a fragrant ground cover or edging plant along garden paths.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Thyme in Mills County, IA?

Mills County is in Zone 5b with an average last frost of April 26. Plan your Lemon Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mills County, IA?

Mills County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 7.

When should I plant Lemon Thyme in Mills County, IA?

In Mills County, IA, plant Lemon Thyme after the last frost (around April 26) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Mills County, IA for Lemon Thyme?

Mills County sits in USDA Zone 5b. Lemon Thyme grows reliably in zones 5a through 9b, so it's a good fit here.

Can Lemon Thyme grow in Mills County's climate?

Yes — Lemon Thyme grows well in Mills County's temperate climate. Mills County averages a 164-day frost-free season, with last frost around April 26 and first frost around October 7.

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Your Mills County Garden Planner — Free

A 22-page printable planner built for Mills County (Zone 5b). 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 Mills County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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