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When to Plant Lemon Thyme in Benton 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.

Benton County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 9, giving you a growing season of approximately 164 days.

At an elevation of 1,230 feet, Benton County receives approximately 36 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Lemon Thyme during the growing season.

Benton County, IA (Zone 5a) Moderate season
164 days
Last Spring Frost April 28
164 growing days
First Fall Frost October 9

Benton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Transplant: Apr 28 🍅 Harvest: Jul 7 – Sep 8
Recommended (50%) ✓ Fits season (24 days to spare)
Transplant: May 5 🍅 Harvest: Jul 14 – Sep 15
Safe Start (90%) ✓ Fits season (19 days to spare)
Transplant: May 19 🍅 Harvest: Jul 28 – Sep 29

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
Lemon Thyme needs ~1,100 GDD — county provides 2,255 GDD Excellent fit

Lemon Thyme Planting Timeline โ€” Benton County, IA

Lemon 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

164 days

Growing Tips for Benton 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

Level Up Your Garden

Frequently Asked Questions

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

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

What planting zone is Benton County, IA?

Benton County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 9.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Benton 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 Benton County, IA. Local conditions may vary. Last updated: April 2026.