Fertilizer for Corn: NPK Guide and Application Rates
Corn is the heaviest nitrogen feeder in the home garden, requiring more nitrogen per square foot than almost any other crop. A critical side-dressing of nitrogen when plants are knee-high makes the difference between full ears and partially filled ones.
Quick Reference
What NPK Ratio is Best for Corn?
The recommended NPK ratio for corn is 16-16-8. The nitrogen-forward 16-16-8 ratio drives leaf and stem development, which corn needs for photosynthesis and canopy growth.
Corn NPK needs shift at each growth stage. Starter fertilizer banded near seed at planting during the Seedling phase, then balanced feed supports tassel and silk development once flowering begins.
NPK by Growth Stage for Corn
| Growth Stage | NPK Ratio | Notes |
|---|---|---|
| Seedling | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Starter fertilizer banded near seed at planting |
| Vegetative | 46N 0P 0K N 46% Nitrogen: leaf and stem growth P 0% Phosphorus: roots and flowers K 0% Potassium: health and disease resistance Learn more about NPK | Heavy nitrogen side-dress when plants reach knee height |
| Flowering | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Balanced feed supports tassel and silk development |
| Fruiting | 5N 5P 10K N 5% Nitrogen: leaf and stem growth P 5% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Potassium for kernel fill |
When Should You Fertilize Corn?
In zone 3, start fertilizing corn in June. In zone 10, begin as early as February. Apply every 3 weeks through the growing season.
Which Zones Can Grow Corn?
Corn grows in USDA zones 3 through 10, spanning a 8-zone range.
Fertilization Start by Zone
| Zone | Start Month |
|---|---|
| Zone 3 | June |
| Zone 4 | May |
| Zone 5 | May |
| Zone 6 | April |
| Zone 7 | April |
| Zone 8 | March |
| Zone 9 | March |
| Zone 10 | February |
What Are the Best Fertilizer Products for Corn?
Look for products with an NPK close to 16-16-8. Espoma Garden-tone is the most popular choice among home gardeners for corn.
- Espoma Garden-tone
- Miracle-Gro All Purpose Plant Food
- Jobe's Organics Vegetable & Tomato
Prices vary by retailer and region. Check current pricing before purchasing.
Container and Raised Bed Adjustments for Corn
Corn is not recommended for containers due to space and pollination requirements
Common Fertilizing Mistakes with Corn
- Skipping the nitrogen side-dressing results in stunted ears with missing kernels
- Placing fertilizer directly on seeds at planting causes poor germination
- Planting in single rows instead of blocks leads to incomplete pollination
Tips for Fertilizing Corn
- Band starter fertilizer 2 inches to the side and 2 inches below the seed at planting
- Side-dress with nitrogen-rich fertilizer when corn reaches 12-18 inches tall
- Plant in blocks of at least 4 rows for proper wind pollination
Organic Fertilizer Alternatives for Corn
Sources
Source:Purdue University ExtensionLast updated: