When to Plant Corn in Mercer County, NJ
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, New Jersey is in USDA Zone 7a. The average last spring frost is April 12 and the first fall frost is October 29, giving you a growing season of approximately 200 days.
At an elevation of 4 feet, Mercer County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Corn during the growing season.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.7
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 Mercer County
How your county's soil matches Corn's growing requirements.
Soil pH
Your soil pH (5.0–6.7) is more acidic than Corn prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Mercer County is excellent for Corn — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (4.0%). Annual compost additions will help Corn.
How to Plant Corn
Succession Planting Corn
Sow every 6.9 weeks. Last sowing by Jul 21 to harvest before frost.
Plant 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 | — | 3.1" | 0" | ❄️ Dormant |
| Feb | — | 3.3" | 0" | ❄️ Dormant |
| Mar | — | 4.1" | 0" | ❄️ Dormant |
| Apr | 6.5" | 4.1" | 2.4" | 💧 Light watering |
| May | 6.5" | 4.1" | 2.4" | 💧 Light watering |
| Jun | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Jul | 6.5" | 4.8" | 1.7" | 💧 Light watering |
| Aug | 6.5" | 4.1" | 2.4" | 💧 Light watering |
| Sep | 6.5" | 3.5" | 3" | 💧 Light watering |
| Oct | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3" | 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, NJ
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 19 | Apr 19 – May 10 |
| Harvest | June 21 | Jun 21 – Aug 16 |
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 · 1-2 times/week
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7a
📆 Growing Season
200 days in Mercer County
Growing Tips for Corn in Mercer County
Direct sow Corn outdoors after April 12 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, NJ?
Mercer County is in Zone 7a with an average last frost of April 12. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mercer County, NJ?
Mercer County, New Jersey is in USDA Hardiness Zone 7a. The average last spring frost is April 12 and first fall frost is October 29.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Mercer County gardeners in Zone 7a organize planting dates, track what's growing, and never miss a planting window.
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