When to plant Corn in Mercer County County,
In Zone 5b (Mercer County County), direct-sow Corn between April 27 and May 18 for spring, after the April 20 last-frost mark.
When to Plant Corn in Mercer County, MO
Top priorities for Mercer County, Missouri gardeners in June
June is a pivotal month for Mercer County, Missouri gardens. Focus on these tasks first and you'll set up the rest of the season for success.
-
Collect corn at their peak
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
July prep starts now
- First harvests: corn
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.
Mercer County, Missouri is in USDA Zone 5b. The average last spring frost is April 20 and the first fall frost is October 14, giving you a growing season of approximately 177 days.
At an elevation of 523 feet, Mercer County receives approximately 41.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Corn during the growing season.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.8
Drainage
Well Drained
Corn 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 Mercer County
How your county's soil matches Corn's growing requirements.
Soil pH
Your soil pH (5.6–6.8) overlaps with Corn's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Mercer County is excellent for Corn — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Corn.
Organic Matter
Organic matter is moderate (2.9%). Annual compost additions will help Corn.
How to Plant Corn
Succession Planting Corn
Sow every 6.9 weeks. Last sowing by Jul 06 to harvest before frost.
Corn Water Budget
Monthly Watering Guide for Corn
Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Corn Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 2" | 0" | ❄️ Dormant |
| Mar | — | 3.2" | 0" | ❄️ Dormant |
| Apr | 6.5" | 4.3" | 2.2" | 💧 Light watering |
| May | 6.5" | 4.8" | 1.7" | 💧 Light watering |
| Jun | 6.5" | 5.1" | 1.4" | 💧 Light watering |
| Jul | 6.5" | 4" | 2.5" | 💧 Light watering |
| Aug | 6.5" | 4.4" | 2.1" | 💧 Light watering |
| Sep | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Oct | 6.5" | 3.2" | 3.3" | 🚿 Regular watering |
| Nov | — | 2.7" | 0" | ❄️ Dormant |
| Dec | — | 2.5" | 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.
Corn 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.
Corn Planting Timeline — Mercer County, MO
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 27 | Apr 27 – May 18 |
| Harvest | June 29 | Jun 29 – Aug 24 |
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
1.5"/week · Only during dry spells
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
177 days in Mercer County
Growing Tips for Corn in Mercer County
Direct sow Corn outdoors after April 20 in Mercer County when soil has warmed and frost danger has passed.
Common pests for Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.
General growing tips
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 Mercer County, MO?
Mercer County is in Zone 5b with an average last frost of April 20. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mercer County, MO?
Mercer County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 20 and first fall frost is October 14.
When should I plant Corn in Mercer County, ?
In Mercer County, , plant Corn after the last frost (around April 20) and before the first frost (around October 14). Best results when soil holds above 50°F.
What growing zone is Mercer County, for Corn?
Mercer County sits in USDA Zone 5b. Corn grows reliably in zones 3a through 11b, so it's a good fit here.
Can Corn grow in Mercer County's climate?
Yes — Corn grows well in Mercer County's temperate climate. Mercer County averages a 177-day frost-free season, with last frost around April 20 and first frost around October 14.
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.