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When to Plant Leeks in Walworth County, WI

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.

Walworth County, Wisconsin is in USDA Zone 5a. The average last spring frost is April 26 and the first fall frost is October 13, giving you a growing season of approximately 170 days.

At an elevation of 1,101 feet, Walworth County receives approximately 39.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Leeks during the growing season.

Walworth County, WI (Zone 5a) Moderate season
170 days
Last Spring Frost April 26
170 growing days
First Fall Frost October 13

Walworth County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (1 days to spare)
Start indoors: Mar 18 Transplant: Apr 22 🍅 Harvest: Jul 22 – Oct 7
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Mar 22 Transplant: Apr 26 🍅 Harvest: Jul 26 – Oct 11
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Aug 11 – Oct 27

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
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 39 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Leeks needs ~1,830 GDD — county provides 2,592 GDD Excellent fit

Leeks Planting Timeline โ€” Walworth County, WI

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 โ€“ Apr 5
Transplant Outdoors April 26 Apr 26 โ€“ May 10
Direct Sow April 12 Apr 12 โ€“ May 3
Fall Sowing August 4 Aug 4 โ€“ Aug 18
Harvest July 26 Jul 26 โ€“ Oct 11

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“150 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

170 days

Growing Tips for Walworth County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Leeks in Walworth County, WI?

Walworth County is in Zone 5a with an average last frost of April 26. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Walworth County, WI?

Walworth County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is April 26 and first fall frost is October 13.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Walworth County gardeners in Zone 5a 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 Walworth County, WI. Local conditions may vary. Last updated: April 2026.