When to Plant Leeks in Ogle County, IL
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.
Ogle County, Illinois is in USDA Zone 5a. The average last spring frost is April 23 and the first fall frost is October 13, giving you a growing season of approximately 173 days.
At an elevation of 890 feet, Ogle County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Leeks during the growing season.
Ogle County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.9
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 Ogle County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (5.9–6.9) overlaps with Leeks's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Ogle County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Leeks will thrive.
How to Plant Leeks
Fall planting: Sow 10 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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 3.5" | 3.9" | 0" | ✅ Rainfall sufficient |
| May | 3.5" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 5" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 3.9" | 0" | ✅ Rainfall sufficient |
| Oct | 3.5" | 3.1" | 0.4" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ogle 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 — Ogle County, IL
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 19 | Mar 19 – Apr 2 |
| Transplant Outdoors | April 23 | Apr 23 – May 7 |
| Direct Sow | April 9 | Apr 9 – Apr 30 |
| Harvest | July 23 | Jul 23 – Oct 8 |
| Fall Sowing | August 4 | Aug 4 – Aug 18 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing 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 5a
📆 Growing Season
173 days in Ogle County
Growing Tips for Leeks in Ogle County
Direct sow Leeks outdoors after April 23 in Ogle County when soil has warmed and frost danger has passed.
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
Check more plant combinations with our Companion Planting Checker →
Leeks in Other Locations
Frequently Asked Questions
When should I plant Leeks in Ogle County, IL?
Ogle County is in Zone 5a with an average last frost of April 23. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ogle County, IL?
Ogle County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 23 and first fall frost is October 13.
Plan Your Garden with Confidence
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