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When to Plant Leeks in Jackson 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.

Jackson County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is October 2, giving you a growing season of approximately 142 days.

At an elevation of 608 feet, Jackson County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Leeks to ensure they mature before fall.

Jackson County, WI (Zone 4b) Short season
142 days
Last Spring Frost May 13
142 growing days
First Fall Frost October 2

Jackson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 24 Transplant: May 5 🍅 Harvest: Aug 4 – Sep 29
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Aug 12 – Oct 7
Safe Start (90%) ✗ May not fit
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Aug 20 – Oct 15

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 Jackson County

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

Soil pH

Your soil pH (6.1โ€“6.7) is within Leeks's preferred range (6.0โ€“7.0).

Soil Texture

The silt loam soil in Jackson County is excellent for Leeks โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.0%) โ€” 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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Leeks needs ~1,560 GDD — county provides 1,846 GDD Good fit

Leeks Planting Timeline โ€” Jackson County, WI

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 โ€“ Apr 15
Transplant Outdoors May 13 May 13 โ€“ May 27
Direct Sow May 6 May 6 โ€“ May 27
Fall Sowing July 10 Jul 10 โ€“ Jul 24
Harvest August 12 Aug 12 โ€“ Oct 7

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 โ€”
July Fall Sowing
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.8"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

90โ€“150 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 4b

๐Ÿ“† Growing Season

142 days in Jackson County

Growing Tips for Leeks in Jackson County

Direct sow Leeks outdoors after May 13 in Jackson County when soil has warmed and frost danger has passed.

Your 142.0-day growing season in Jackson 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Leeks in Jackson County, WI?

Jackson County is in Zone 4b with an average last frost of May 13. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jackson County, WI?

Jackson County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is October 2.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jackson County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Jackson County, WI. Local conditions may vary. Last updated: April 2026.