When to plant Leeks in Springfield, IL
Springfield gardeners should plant Leeks between April 1 and April 22 in spring. With Springfield's Zone 6a climate (last frost April 15), Leeks needs 90–150 days to mature — plant by May 20 for a full harvest. A second sowing from August 8 to August 22 extends the harvest into fall.
When to Plant Leeks in Springfield, 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.
Springfield, Illinois is in USDA Zone 6a. The average last spring frost is April 15 and the first fall frost is October 17, giving you a growing season of approximately 185 days.
At an elevation of 1,204 feet, Sangamon County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Leeks during the growing season.
Springfield Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.2
Drainage
Well Drained
Monthly Watering Guide for Leeks
Leeks needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Leeks Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.9" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 5.8" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.3" | 1" | 💧 Light watering |
| Oct | 4.3" | 3.3" | 1" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Sangamon County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Leeks Planting Timeline — Springfield, IL
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | April 15 | Apr 15 – Apr 29 |
| Direct Sow | April 1 | Apr 1 – Apr 22 |
| Harvest | July 15 | Jul 15 – Sep 30 |
| Fall Sowing | August 8 | Aug 8 – Aug 22 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 6a
📆 Growing Season
185 days in Sangamon County
Growing Tips for Springfield
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
When should I plant Leeks in Springfield, IL?
In Springfield, IL, plant Leeks after the last frost (around April 15) and before the first frost (around October 17). Best results when soil holds above 50°F.
What growing zone is Springfield, IL for Leeks?
Springfield sits in USDA Zone 6a. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.
Can Leeks grow in Springfield's climate?
Yes — Leeks grows well in Springfield's temperate climate. Springfield averages a 185-day frost-free season, with last frost around April 15 and first frost around October 17.
Your Sangamon County Garden Planner — Free
A 22-page printable planner built for Sangamon County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.