How to Grow Sweet Corn
A tip sheet on how to grow and care for sweet corn.
Sweet Corn (Zea Mays)
- Family: Poaceae (Grass)
- Season: Warm
- Ease of growing: Medium
- Nutrient needs: High
- Water needs: Medium
- Common propagation: Seed
- Germination temperatures: 50°F to 95°F
- Germination time: 3 to 10 days
- Viability: 1 to 3 years
- Direct sow: May to July
- Weeks to grow transplant: 3 to 4
- Start: April
- Plant out: May
- Typical spacing: 6” on 30’’ rows
- Plants per square foot: 1
- Days to harvest: 60 to 100 from seed
Sweet corn varieties are categorized primarily according to kernel color (yellow, white or both) and sweetness or texture. In addition to traditional varieties, plant breeders have developed “sugary enhanced” (se) varieties with increased tenderness and “super sweet” (sh2) varieties which have heightened sweetness and slower conversion of sugar to starch after harvest. “Synergistic” varieties combine the tenderness of se and sh2 types.
Preparation and planting
It is important when planting super sweet and white varieties to separate them from other types since cross pollination will result in expression of yellow and starchy characteristics. Separate varieties by at least 100 feet or plant so that maturity time differs by at least 10 days. Corn does well on most soils but yields best on loose, well drained loams. It is usually direct seeded, though early corn can be grown by transplanting and protecting young plants with row covers. Corn is a heavy feeder, and it will benefit from being planted after legumes. To help insure adequate pollination, at least 10 plants should be sown in a group at each planting. For continuous harvest, plant successive plantings at the time that the previous planting emerges.
To enhance growth, side-dress with nitrogen one month after the plants are up. Corn is relatively drought-tolerant, but adequate moisture is very important after silking to ensure good pollination and prevent poorly filled ears.
Insects: Seed corn maggots, cutworms, armyworms, flea beetles, corn leaf aphids, European corn borers, corn earworms, corn rootworm adults
Diseases: Stewarts wilt and corn smut
Harvest and storage
Sweet corn is ready when the silks have dried down and the kernels are plump, about three weeks after pollination. Harvest early in the morning and cool immediately to maintain quality. For most varieties, sugars in the kernel begin converting to starch immediately after picking. Super sweet varieties convert more slowly. They may be stored in a refrigerator for a few days without much loss of flavor and quality.
Developed by James Manning, Undergraduate Research Assistant, and Daniel Brainard, Vegetable Extension Specialist; MSU Department of Horticulture; Gary Heilig, MSU Extension educator.