MSU Extension

The corn family

Sweet corn is the only grain that is eaten fresh as a vegetable. There are several types of corn.

Field corn is not eaten fresh. It is also referred to as dent corn because of the appearance of the dried kernels. Field corn is used as livestock or poultry feed or dried and ground into corn meal for people.

Indian corn or flint corn is often brightly colored and is starchy like field corn.

Popcorn is grown and dried to be eaten popped.

Sweet corn is the most popular corn used by many gardeners. Sweet corn is grown in most vegetable gardens and is eaten fresh. It is one of the most popular vegetables in the United States.

Corn needs a big garden

Since each plant produces only one or two ears, it would be necessary to plant at least 80 feet of row to produce enough sweet corn for a family of four. Corn is wind pollinated. It must be planted in blocks or squares of three or more rows. Do not plant in one or two rows because the ears will not be pollinated, meaning that there will be few kernels on each ear.

Corn is a warm weather crop

Sweet corn is a warm season crop that requires warm soils and full sun all day. For an early crop, although frost can injure seedlings, a small number of seeds can be planted early. You are gambling on the unpredictable weather. It’s risky, but it can give an earlier harvest. 

Wait to plant most of the corn in late May to reduce the risk of frost damage.

Kinds of sweet corn

Sweet corn can be divided by colors, sweetness and time of the season it becomes ripe. Kernels of different varieties will be yellow, white or a yellow and white mixture often called bi-color. In regards to sweetness, there is standard, sugar-enhanced and the sweetest which are called super sweet. The sugar-enhanced and super sweets often do not germinate well in cool soil. Corn is also divided into early, mid-season and late varieties.

Planting

When planting, follow the directions on the back of the seed package or plant seeds 1.5 to two inches deep, five to six inches apart in rows that are two to three feet apart. Thin plants to 10 to 12 inches apart.

Many people find that the super sweet corn varieties do not germinate well. If seeds do not germinate, plant when the soil is warm to the touch and space the seeds closer than recommended.

Succession planting

To lengthen harvest, plant early, mid-season and late varieties all at the same time. Make successive plantings of mid-season and or late varieties until late June. Wait until each planting is about two inches high before planting more. 

Keys to success

• Plant four, short rows rather than long, single or double rows.
• Plant mostly mid- and late season varieties for the best quality.

The basics

Corn will grow most soils if it is well-drained. Corn grows best in loam soils. For good germination of seeds, the soil needs to be 60°F or above.

Corn is a heavy feeder, especially of nitrogen (fertilizer). Follow your soil test recommendations or use two pounds of 5-20-20 fertilizer per 100 square feet of soil. When the plants are knee high or at the beginning of July, apply a high nitrogen fertilizer (4 lbs of 21-0-0 or 2 lbs of 46-0-0) per 100 square feet along the sides of the rows.

Keep corn free of weeds and grasses. Cultivate with a hoe, but be careful not to injure shallow roots. A mulch of straw or similar material can be used to control weeds and hold in moisture. Do not remove suckers (side shoots), as this may reduce yields.

Corn needs lots of water, especially from the time the tassels (silky, hair-like material growing out of the top of the ear of corn) appear until harvest. An inch of water per week, either from rain or the hose will ensure proper moisture. More water may be required on sandy soil.

Harvesting

Harvest sweet corn after the silks on the ear turn brown and are dry. Corn kernels should be round and filled out. Kernels that are square may be past their prime and the sugars converted to starch. Husks should appear fresh and not dried out.

Storage

The quality of sweet corn decreases very rapidly after picking. The sugars convert to starch and the unique flavor is lost. Use immediately or store for a short time in the refrigerator. Fresh sweet corn can be frozen or canned, if done correctly.

Problems

To help prevent seeds from rotting in cold soil early in the spring, it is possible to use seeds treated with a fungicide. Those that are treated will be colored, like a brilliant pink. The package will also have that information on it.

Cover the seeds well with soil to deter birds or animals from eating the seeds. If loss of seeds to birds or animals is a continuing problem in a small garden, use a narrow strip of hardware screening or chicken wire over the row until the corn plants just begin to emerge. Eaves troughs covers work well for this, too. Be sure to remove screening before the corn plants sprout and are damaged.

Insects or animals may be troublesome, especially corn earworms and raccoons. Contact your local Extension office for information on how to manage these pests.

Originally developed by Lee Taylor and adapted by Gretchen Voyle. Revised by Hannah Stevens.