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Sweet Corn

Think of summer vegetables, and sweet corn usually comes to mind. Corn was a main source of food for early American people and was one of the few “native” vegetables to spread throughout the world. Sweet corn is rich in carbohydrates and sugars and contains vitamins A, B, and C, minerals and protein. It is an excellent vegetable for freezing or canning, extending this summer treat for year-round use.

Sweet corn is not well adapted to a small garden area, and corn planted too close will produce poorly. Consider whether you want to invest the space to grow sweet corn if your garden area is limited.

Varieties

Many new hybrid varieties are easy to grow and yield well. Several factors contribute to differences among varieties, including growing time or “days to maturity.” For a continuous supply of corn, consider an early maturing (65 to 75 day) variety. Additional plantings of mid-season (75 to 85 day) varieties can be planted for succeeding crops. The first planting can include both, for a continual supply of corn.

Soils and Fertilizer

Sweet corn thrives in deep, rich soils, but any well drained garden soil should produce sweet corn. Sandy soils are better for early crops since they warm up faster in the spring.

Corn responds to high levels of fertilizer. It is best to provide a “base application” of fertilizer before planting. Apply to the soil before tilling and work the fertilizer in. Use 1 to 2 pounds of 10-10-10 or 12-12-12 fertilizer per 100 square feet unless you have specific recommendations from a soil test. After planting, corn usually benefits from a “side-dressing” of additional fertilizer along the row as the crop is growing. Use 3 pounds of ammonium nitrate fertilizer per 100 feet of row when the corn is 8 to 12 inches tall and again just prior to tasseling in sandy soils or wet years, since fertilizer can be washed from the soil under these conditions.

Planting

At the earliest, it should be planted a week before the average frost date in your area. For extra-sweet types, delay planting until soil temperatures are above 60°F. For successive plantings, you will find that earlier planted corn will be slower to emerge, so wait until one planting is 1 to 2 inches tall before planting the next.

Plant kernels from 1 to 2 inches deep, spaced 8 to 12 apart in rows 30 to 40 inches wide. A yield of about 30 ears may be expected for every 25 feet of row planted. Three to four rows 25 feet long may provide corn for an average family.

Cultivation and Watering

Weeds compete with corn and should be controlled. Corn is easy to hoe or cultivate, and several excellent herbicides are available for larger plantings. Corn usually needs 1 to 11⁄2 inches of water per week to produce a heavy yield. If rainfall is less than that, water to soak the soil and check that the water has penetrated 12 to 18 inches.

Harvest

Sweet corn should be harvested when the juice in the kernel appears milky as you puncture a kernel with your thumbnail. This “milk” stage lasts only a short time, especially in hot weather, so check the planting regularly. Immature corn will produce a watery juice when punctured, while over-mature corn will produce a doughy, tough kernel. When silks dry to a deep, chocolate brown, feel the ends of the ears for fullness, indicating maturity. To remove ears from the stalk, twist the ear and bend it down sharply. This will not damage the stalk if other ears still remain. Use the corn immediately. Sugars in sweet corn are lost rapidly; most varieties can lose half their sugar in 10 to 12 hours if not properly cared for. Pick corn in the early morning and refrigerate it as it is harvested or begin processing immediately. Corn can be cooled quickly in cold water if harvesting is done during the heat of the day.

By Charles Marr Extension Specialist

Kansas State University Agricultural Experiment Station and Cooperative Extension Service

MF-669 Revised November 1994