When to plant Corn in Union County, IL
In Zone 7a (Union County), direct-sow Corn between April 17 and May 8 for spring, after the April 10 last-frost mark.
When to Plant Corn in Union County, IL
Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.
Union County, Illinois is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 21, giving you a growing season of approximately 194 days.
At an elevation of 1,017 feet, Union County receives approximately 34.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Corn during the growing season.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.1
Drainage
Well Drained
How Much Corn to Grow
For a family of 4, plant approximately 60 corn plants in about 120 sq ft. In Union County's 194-day season, you'll have plenty of time for a full harvest. Plan your garden layout →
Monthly Watering Guide for Corn
Corn needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.6" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3" | 1.3" | 💧 Light watering |
| May | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jul | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Aug | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Sep | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Oct | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Union County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Corn Planting Timeline — Union County, IL
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 17 | Apr 17 – May 8 |
| Harvest | June 19 | Jun 19 – Aug 14 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 7a
📆 Growing Season
194 days in Union County
Growing Tips for Union County
Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Corn in Other Locations
Frequently Asked Questions
When should I plant Corn in Union County, IL?
Union County is in Zone 7a with an average last frost of April 10. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, IL?
Union County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 21.
When should I plant Corn in Union County, IL?
In Union County, IL, plant Corn after the last frost (around April 10) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Union County, IL for Corn?
Union County sits in USDA Zone 7a. Corn grows reliably in zones 3a through 11b, so it's a good fit here.
Can Corn grow in Union County's climate?
Yes — Corn grows well in Union County's temperate climate. Union County averages a 194-day frost-free season, with last frost around April 10 and first frost around October 21.
Your Union County Garden Planner — Free
A 22-page printable planner built for Union County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.