Mario Bautista
Is there any vegetable that screams Ohio summer more than sweet corn eaten on the cob? Some gardeners might argue that the tomato is the more popular vegetable grown in Ohio, and it is the state fruit of Ohio, but for me, it isn’t summer until I bite into my first ear of Ohio-grown sweet corn.
If you are a fan of eating sweet corn, you may want to take a stab at growing a patch of sweet corn in a corner of your vegetable garden if you have enough space.
Sweet corn is a warm-season annual crop that produces ears of yellow, white or bicolored kernels. Also known as maize, corn is native to the Americas and has been cultivated in Central America since 3500 BC.
It was an important food of the Incas, Aztecs and Mayas of Mexico, as well as the cliff dwellers of the southwestern United States. Iroquois in Pennsylvania and New York grew a variety of sweet corn that turned blue as it matured.
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Corn is famous as one of “the three sisters” of corn, squash and beans grown together by Native Americans. In the 1500s, corn was taken to Spain, and from there, it was quickly introduced into France and Italy. Corn currently ranks first in world-grain production, followed by wheat and rice.
Cultural requirements
A long frost-free growing season is necessary to grow sweet corn, so it should be planted in Greater Columbus gardens in mid to late May, when the chance of late frost has past and soil temperatures are above 65 degrees.
Sweet corn grows best in well-drained soils with a fair amount of organic matter and a pH level between 5.8 to 7.0. If your garden soil lacks organic matter, consider amending it with compost or composted manure. Never use fresh manure during the growing season, as it could contain harmful bacteria or viable weed seeds.
Sweet corn should be planted in an area of the garden which receives direct sunlight for at least eight hours each day. For optimum growth, soil where sweet corn is planted should be consistently moist, as corn plants suck up a lot of water.
Direct seeding
It is best to sow corn directly into garden soil, as opposed to starting corn seed indoors and planting transplants. Seeds should be planted 1 inch deep and about 8-10 inches apart, with rows 24 to 30 inches apart in a home garden.
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If you have enough space in your garden, consider planting an additional crop of corn two weeks after your first planting to extend the harvest season. (If you don’t have enough space in your garden, pull out the tomato plants and plant more sweet corn instead of tomatoes!)
Because corn is pollinated by the wind, not insects, it is important to plant corn in blocks of at least four rows. Wind moves corn pollen from the tassel at the top of the plant to the silks of the ears in order for kernels to develop on the ear.
Avoid planting one or two long rows of corn, as much of its pollen will be blown out of the row, instead of onto nearby corn silks, which will cause ears to have blank areas where kernels did not form.
Prior to seeding, apply four pounds of 10-10-10 fertilizer per 100 square feet. The fertilizer should be broadcast evenly and worked into the top 2 or 3 inches of soil.
Choose your sweetness
There are many different varieties of hybrid sweet corn, and all can be classified by one of four types: sugary (su), sugar-enhanced (se), shrunken (sh) or synergistic (sy). Each type of sweet corn contains a different level of sucrose, or sugar, changing the flavor and texture of the corn. The type of seed will be listed on the seed packet.
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Sugary (su) sweet corn is the classic sweet corn, which grows vigorously and is fairly stress resistant. The kernels are less sweet and the sugars quickly turn to starch after harvest, so they need to be eaten right after picking.
Silver queen and butter and sugar are popular varieties of sugary sweet corn. Sugar-enhanced (se) sweet corn is more sweet than sugary varieties and keeps its sweetness for a longer period of time after harvest. Kandy korn is a popular sugar-enhanced variety of sweet corn.
Shrunken (sh) varieties are the sweetest varieties of sweet corn, containing two or three times more sugar than sugary varieties. Shrunken varieties are often called supersweet varieties. The sugar in their kernels lasts for up to a week after harvest and the kernels tend to be more crunchy. Sweet sunshine and honey ‘n pearl are popular shrunken varieties of sweet corn.
Synergistic (sy) varieties combine sugar-enhanced with one of the other two types to create varieties, which have the best traits of both varieties. While the sugar content in synergistic varieties is higher than other types of sweet corn, sugars take longer to build up and kernels can be watery if harvested too early. Popular synergistic varieties include allure and sweetness.
Managing sweet corn
Consistent soil moisture will encourage corn plants to develop larger, thicker ears, so be sure to keep corn watered when rainfall is not adequate. Corn plants require up to 2 inches of water per week, which is more than other plants in the vegetable garden.
Additional water may be needed during periods of especially hot weather, or if your soil is sandy.
Watch for signs of nitrogen deficiency, such as yellowing of leaves. Corn will respond to a side-dressing of a nitrogen-rich source of fertilizer when plants are approximately 12 inches tall.
Apply 8 ounces of 10-10-10 fertilizer to every 10 linear feet of row. To avoid burning roots, fertilizer should be placed 3-4 inches away from the plant on each side.
The roots of corn plants are shallow and can easily be damaged by cultivation. Instead of hoeing weeds, weed corn plants by hand until the plants are large enough to shade the soil and prevent germination of additional weeds.
Harvesting sweet corn
The warmer the air, the more quickly sweet corn matures. Corn is typically ripe and ready for harvest two to three weeks after it starts to silk, sooner if temperatures are excessively hot. When two ears develop on the stalk, the upper ear typically matures a few days earlier than the lower one.
At harvest, ears should be more rounded or blunt, not pointed, with tassels turning brown and kernels full and milky. Prepare the ears for eating or preserving immediately after harvest.
Mike Hogan is Extension Educator, Agriculture and Natural Resources and associate professor with Ohio State University Extension.
hogan.1@osu.edu
