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When to Plant Brussels Sprouts in Brown County, WI

Brown County, Wisconsin Zone 5b May

Your May gardening checklist

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Brown County, Wisconsin.

Avg. last frost May 8
Avg. first frost October 6
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Time to transplant brussels sprouts

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

June will be here before you know it — start on
  • Starting indoors: brussels sprouts

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

Brown County, Wisconsin is in USDA Zone 5b. The average last spring frost is May 8 and the first fall frost is October 6, giving you a growing season of approximately 151 days.

At an elevation of 1,235 feet, Brown County receives approximately 34.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.

Brown County, WI (Zone 5b) Moderate season
151 days
Last Spring Frost May 8
151 growing days
First Fall Frost October 6
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Brown County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jul 29 – Sep 23
Recommended (50%) ✓ Fits season (4 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Aug 7 – Oct 2
Safe Start (90%) ✓ Fits season (2 days to spare)
Start indoors: Apr 19 Transplant: May 24 🍅 Harvest: Aug 23 – Oct 18

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.

Soil Compatibility in Brown County

How your county's soil matches Brussels Sprouts's growing requirements.

Soil pH

Your soil pH (6.0–6.8) is within Brussels Sprouts's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Brown County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.7%) — Brussels Sprouts will thrive.

How to Plant Brussels Sprouts

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Brussels Sprouts

Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Brussels Sprouts Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 3.9" 3.9" 0" ✅ Rainfall sufficient
Jun 3.9" 4.6" 0" ✅ Rainfall sufficient
Jul 3.9" 3.6" 0.3" 💧 Light watering
Aug 3.9" 3.8" 0.1" 💧 Light watering
Sep 3.9" 3.3" 0.6" 💧 Light watering
Oct 3.9" 2.6" 1.3" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Brown County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Brussels Sprouts Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Brussels Sprouts needs ~1,430 GDD — county provides 1,963 GDD Excellent fit

Brussels Sprouts Planting Timeline — Brown County, WI

Brussels Sprouts Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 8 May 8 – May 22
Direct Sow April 24 Apr 24 – May 15
Harvest August 7 Aug 7 – Oct 2
Fall Sowing July 28 Jul 28 – Aug 11

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Natural rainfall sufficient

📅 Days to Maturity

90–130 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

151 days in Brown County

Growing Tips for Brussels Sprouts in Brown County

Direct sow Brussels Sprouts outdoors after May 08 in Brown County when soil has warmed and frost danger has passed.

Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Brussels Sprouts in Brown County, WI?

Brown County is in Zone 5b with an average last frost of May 8. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.

What planting zone is Brown County, WI?

Brown County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is May 8 and first fall frost is October 6.

🌱

Your Brown County Garden Planner — Free

A 24-page printable planner built for Brown 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 Brown County, WI. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.