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When to Plant Brussels Sprouts in Koochiching County, MN

Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.

Koochiching County, Minnesota is in USDA Zone 3a. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 508 feet, Koochiching County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79ยฐF, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.

Koochiching County, MN (Zone 3a) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18

Koochiching County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 4 Transplant: May 16 🍅 Harvest: Aug 15 – Sep 19
Recommended (50%) ✗ May not fit
Start indoors: Apr 10 Transplant: May 22 🍅 Harvest: Aug 21 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: May 4 Transplant: Jun 15 🍅 Harvest: Sep 14 – Oct 19

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
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Brussels Sprouts needs ~1,018 GDD — county provides 1,100 GDD Good fit

Brussels Sprouts Planting Timeline โ€” Koochiching County, MN

Brussels Sprouts 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 June 26 Jun 26 โ€“ Jul 10
Harvest August 21 Aug 21 โ€“ Sep 25

Plant 1" deep ยท 15" apart ยท Rows 24" 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 Fall Sowing
July Fall Sowing
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“130 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 3a

Growing Season

119 days

Growing Tips for Koochiching County

Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Brussels Sprouts in Koochiching County, MN?

Koochiching County is in Zone 3a with an average last frost of May 22. Plan your Brussels Sprouts planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Koochiching County, MN?

Koochiching County, Minnesota is in USDA Hardiness Zone 3a. The average last spring frost is May 22 and first fall frost is September 18.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Koochiching County gardeners in Zone 3a 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 Koochiching County, MN. Local conditions may vary. Last updated: April 2026.