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When to Plant Brussels Sprouts in Kewaunee County, WI

Kewaunee County, Wisconsin Zone 5b May

This month in Kewaunee County, Wisconsin

Your garden in Kewaunee County, Wisconsin is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 3
Avg. first frost October 11
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Plant out brussels sprouts

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

June prep starts now
  • 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.

Kewaunee County, Wisconsin is in USDA Zone 5b. The average last spring frost is May 3 and the first fall frost is October 11, giving you a growing season of approximately 161 days.

At an elevation of 950 feet, Kewaunee County receives approximately 39.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.

Kewaunee County, WI (Zone 5b) Moderate season
161 days
Last Spring Frost May 3
161 growing days
First Fall Frost October 11
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Kewaunee County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jul 27 – Sep 21
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Aug 2 – Sep 27
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Apr 15 Transplant: May 20 🍅 Harvest: Aug 19 – Oct 14

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 Kewaunee County

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

Soil pH

Your soil pH (5.8–7.1) overlaps with Brussels Sprouts's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — 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
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4" 0" ❄️ Dormant
May 3.9" 5" 0" ✅ Rainfall sufficient
Jun 3.9" 5.4" 0" ✅ Rainfall sufficient
Jul 3.9" 4.5" 0" ✅ Rainfall sufficient
Aug 3.9" 4.4" 0" ✅ Rainfall sufficient
Sep 3.9" 2.9" 1" 💧 Light watering
Oct 3.9" 3.3" 0.6" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Kewaunee 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 ~1,265 GDD — county provides 1,851 GDD Excellent fit

Brussels Sprouts Planting Timeline — Kewaunee County, WI

Brussels Sprouts Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 3 May 3 – May 17
Direct Sow April 19 Apr 19 – May 10
Harvest August 2 Aug 2 – Sep 27
Fall Sowing August 2 Aug 2 – Aug 16

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June
July
August Fall Sowing Harvest
September Harvest
October
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: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

161 days in Kewaunee County

Growing Tips for Brussels Sprouts in Kewaunee County

Direct sow Brussels Sprouts outdoors after May 03 in Kewaunee 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 Kewaunee County, WI?

Kewaunee County is in Zone 5b with an average last frost of May 3. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kewaunee County, WI?

Kewaunee County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is May 3 and first fall frost is October 11.

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Your Kewaunee County Garden Planner — Free

A 24-page printable planner built for Kewaunee 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 Kewaunee 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.