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When to Plant Leeks in Chippewa County, WI

Chippewa County, Wisconsin Zone 4b May

What to do in May

Welcome to May in Zone 4b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 15
Avg. first frost September 28
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs
  1. Transplant leeks outside

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

  2. Put leeks seeds straight in the ground

    These tolerate cool soil, so you're not gambling by sowing now.

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

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Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Chippewa County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.

At an elevation of 916 feet, Chippewa County receives approximately 40.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Chippewa County, WI (Zone 4b) Short season
136 days
Last Spring Frost May 15
136 growing days
First Fall Frost September 28

Chippewa County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 10 – Oct 5
Recommended (50%) ✗ May not fit
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Aug 14 – Oct 9
Safe Start (90%) ✗ May not fit
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Aug 25 – Oct 20

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 Chippewa County

How your county's soil matches Leeks's growing requirements.

Soil pH

Your soil pH (5.8–6.7) overlaps with Leeks's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Leeks.

Organic Matter

Organic matter is excellent (4.4%) — Leeks will thrive.

How to Plant Leeks

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

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

Monthly Watering Guide for Leeks

Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Leeks Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 3.5" 4.3" 0" ✅ Rainfall sufficient
Jun 3.5" 5.3" 0" ✅ Rainfall sufficient
Jul 3.5" 4.2" 0" ✅ Rainfall sufficient
Aug 3.5" 4.2" 0" ✅ Rainfall sufficient
Sep 3.5" 4.3" 0" ✅ Rainfall sufficient
Oct 3.4" 0" ❄️ Dormant
Nov 2.5" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

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

Leeks 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.

Leeks needs ~1,470 GDD — county provides 1,666 GDD Good fit

Leeks Planting Timeline — Chippewa County, WI

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest August 14 Aug 14 – Oct 9
Fall Sowing July 6 Jul 6 – Jul 20

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

136 days in Chippewa County

Growing Tips for Leeks in Chippewa County

Direct sow Leeks outdoors after May 15 in Chippewa County when soil has warmed and frost danger has passed.

Your 136.0-day growing season in Chippewa County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in Chippewa County, WI?

Chippewa County is in Zone 4b with an average last frost of May 15. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Chippewa County, WI?

Chippewa County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 28.

🌱

Your Chippewa County Garden Planner — Free

A 24-page printable planner built for Chippewa County (Zone 4b). 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 Chippewa 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.