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When to Plant Thyme in Alpena County, MI

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.

Alpena County, Michigan is in USDA Zone 5a. The average last spring frost is May 19 and the first fall frost is October 3, giving you a growing season of approximately 137 days.

At an elevation of 984 feet, Alpena County receives approximately 31.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Thyme during the growing season.

Alpena County, MI (Zone 5a) Short season
137 days
Last Spring Frost May 19
137 growing days
First Fall Frost October 3

Alpena County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 20 🍅 Harvest: Jul 29 – Sep 30
Recommended (50%) ✗ May not fit
Transplant: May 26 🍅 Harvest: Aug 4 – Oct 6
Safe Start (90%) ✓ Fits season (4 days to spare)
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.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.0″/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 1,986 GDD Excellent fit

Thyme Planting Timeline โ€” Alpena County, MI

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 26 May 26 โ€“ Jun 9
Harvest August 4 Aug 4 โ€“ Oct 6

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 Transplant Outdoors
July โ€”
August Harvest
September Harvest
October Harvest
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

137 days

Growing Tips for Alpena 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 Alpena County, MI?

Alpena County is in Zone 5a with an average last frost of May 19. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Alpena County, MI?

Alpena County, Michigan is in USDA Hardiness Zone 5a. The average last spring frost is May 19 and first fall frost is October 3.

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Plan Your Garden with Confidence

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