When to plant Leeks in Viola,
Plant Leeks in Viola from April 3 to April 24 in spring. Viola sits in USDA Zone 5b, with last frost around April 17 and first frost on October 15. A second sowing from August 6 to August 20 extends the harvest into fall.
When to Plant Leeks in Viola, IL
Viola, IL gardeners: here's your June plan
Here's what deserves your attention in Viola, IL this month. Everything below is tailored to Zone 5b and timed around your local frost dates.
July will be here before you know it — start on
- First harvests: leeks
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.
Viola, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.
At an elevation of 777 feet, Mercer County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Leeks to ensure they mature before fall.
Viola Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
Drainage
Well Drained
Leeks 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 Viola
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (6.3–6.7) is within Leeks's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Mercer County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (4.0%). Annual compost additions will help Leeks.
How to Plant Leeks
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Leeks 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 | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 3.5" | 3.7" | 0" | ✅ Rainfall sufficient |
| May | 3.5" | 4" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 3.7" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 3.4" | 0.1" | 💧 Light watering |
| Oct | 3.5" | 2.5" | 1" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Mercer 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 — Viola, IL
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 13 | Mar 13 – Mar 27 |
| Transplant Outdoors | April 17 | Apr 17 – May 1 |
| Direct Sow | April 3 | Apr 3 – Apr 24 |
| Harvest | July 17 | Jul 17 – Oct 2 |
| Fall Sowing | August 6 | Aug 6 – Aug 20 |
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 | 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
181 days in Mercer County
Growing Tips for Leeks in Viola
Direct sow Leeks outdoors after April 17 in Mercer 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
When should I plant Leeks in Viola, ?
In Viola, , plant Leeks after the last frost (around April 17) and before the first frost (around October 15). Best results when soil holds above 50°F.
What growing zone is Viola, for Leeks?
Viola sits in USDA Zone 5b. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.
Can Leeks grow in Viola's climate?
Yes — Leeks grows well in Viola's temperate climate. Viola averages a 181-day frost-free season, with last frost around April 17 and first frost around October 15.
Your Mercer County Garden Planner — Free
A 22-page printable planner built for Mercer County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.