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When to Plant Tatsoi in Ontonagon County, MI

Tatsoi is a compact Asian green forming beautiful rosettes of dark, spoon-shaped leaves with a mild mustard flavor. It is extremely cold-hardy and versatile.

Ontonagon County, Michigan is in USDA Zone 4a. The average last spring frost is May 22 and the first fall frost is September 28, giving you a growing season of approximately 129 days.

At an elevation of 502 feet, Ontonagon County receives approximately 42 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Tatsoi to ensure they mature before fall.

Ontonagon County, MI (Zone 4a) Short season
129 days
Last Spring Frost May 22
129 growing days
First Fall Frost September 28

Ontonagon County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (54 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jun 22 – Jul 27
Recommended (50%) ✓ Fits season (59 days to spare)
Start indoors: Apr 10 Transplant: May 22 🍅 Harvest: Jun 26 – Jul 31
Safe Start (90%) ✓ Fits season (56 days to spare)
Start indoors: Apr 25 Transplant: Jun 6 🍅 Harvest: Jul 11 – Aug 15

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
1.0″/week
Rainfall provides
1.4″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Tatsoi needs ~425 GDD — county provides 1,290 GDD Excellent fit

Tatsoi Planting Timeline โ€” Ontonagon County, MI

Tatsoi Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 โ€“ Apr 24
Transplant Outdoors May 22 May 22 โ€“ Jun 5
Direct Sow May 15 May 15 โ€“ Jun 5
Fall Sowing July 6 Jul 6 โ€“ Jul 20
Harvest June 26 Jun 26 โ€“ Jul 31

Plant 0.5" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow Harvest
July Fall Sowing Harvest
August โ€”
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

35โ€“50 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4a

Growing Season

129 days

Growing Tips for Ontonagon County

Direct sow in spring or fall. Tatsoi tolerates frost down to 15F. Harvest outer leaves or cut whole rosettes. Excellent in salads, stir-fries, or lightly wilted.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Tatsoi in Ontonagon County, MI?

Ontonagon County is in Zone 4a with an average last frost of May 22. Plan your Tatsoi planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Ontonagon County, MI?

Ontonagon County, Michigan is in USDA Hardiness Zone 4a. The average last spring frost is May 22 and first fall frost is September 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Ontonagon County gardeners in Zone 4a 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 Ontonagon County, MI. Local conditions may vary. Last updated: April 2026.