When to Plant Leeks in Douglas 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.
Douglas County, Wisconsin is in USDA Zone 3b. The average last spring frost is May 16 and the first fall frost is September 28, giving you a growing season of approximately 135 days.
At an elevation of 1,147 feet, Douglas County receives approximately 31.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Leeks to ensure they mature before fall.
Douglas County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.7
Drainage
Well Drained
Plant Planting Risk Windows
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 Douglas County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (5.9–6.7) overlaps with Leeks's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Douglas County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Leeks will thrive.
How to Plant Leeks
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 3.4" | 0" | ❄️ Dormant |
| May | 3.5" | 3.4" | 0.1" | 💧 Light watering |
| Jun | 3.5" | 3.6" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 3.2" | 0.3" | 💧 Light watering |
| Aug | 3.5" | 3.1" | 0.4" | 💧 Light watering |
| Sep | 3.5" | 2.7" | 0.8" | 💧 Light watering |
| Oct | — | 2.9" | 0" | ❄️ Dormant |
| Nov | — | 2.4" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Douglas 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 Planting Timeline — Douglas County, WI
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 4 | Apr 4 – Apr 18 |
| Transplant Outdoors | May 16 | May 16 – May 30 |
| Direct Sow | May 9 | May 9 – May 30 |
| Harvest | August 15 | Aug 15 – Sep 19 |
| Fall Sowing | July 6 | Jul 6 – Jul 20 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | — |
| 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 3b
📆 Growing Season
135 days in Douglas County
Growing Tips for Leeks in Douglas County
Direct sow Leeks outdoors after May 16 in Douglas County when soil has warmed and frost danger has passed.
Your 135.0-day growing season in Douglas 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
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Leeks in Other Locations
Frequently Asked Questions
When should I plant Leeks in Douglas County, WI?
Douglas County is in Zone 3b with an average last frost of May 16. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Douglas County, WI?
Douglas County, Wisconsin is in USDA Hardiness Zone 3b. The average last spring frost is May 16 and first fall frost is September 28.
Plan Your Garden with Confidence
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