There are three types of sweet corn. They are normal sugary (su), sugary enhanced (se) and supersweet (sh2). These types refer to the sugar content and sweet flavor in the kernels when mature. The normal sugary (su) sweet corn will convert kernel sugar to starch immediately after harvest. This means the sweet flavor is rapidly lost. The supersweet or “shrunken two” (sh2) type was discovered in 1950 by Dr. J. R. Laugham, University of Illinois, using traditional breeding techniques. He discovered a corn containing more sugar, and when dried, the kernels shrunk, thus the name shrunken. These high-sugar types were named supersweet because the sugar content can be twice as great as normal sugary (su) sweet corn at peak maturity. The supersweet types slow down the conversion of sugar to starch so that the sweet flavor lasts longer after harvest.
About 10 years later, again at the University of Illinois, Dr. A.M. Rhodes bred a corn with sweet flavor and tender texture. Dr. Rhodes called this new type, sugary enhanced (se) genetic types. The (se) corn has higher sugar levels, and because of this, the sweet flavor will last longer after harvest. Overall (se) sugary enhanced types have increased in popularity because they combine the sweet flavor with ease of growing for gardeners.
For the new millennium, there are hybrids that combine two or three types of sweet corn. One variety can offer gardeners a combination of sugary enhanced (se) and supersweet (sh2) or all three types, adding normal sugary (su) to the hybrid. The advantages to the gardener are the higher sugar levels provide a sweet flavor but with the ease of growing normal sugary (su) types. Fresh sweet corn of these synergistic hybrids are mouth-watering sweet and not as “crunchy” as older supersweet (sh2) types.
Gardeners can grow white, yellow, bicolor or multicolored kernel corn. Provided a gardener has sufficient space, an early (65 to 70 days), midseason (75 to 85 days) and late-season (85 to 100 days) variety could be grown to have a constant harvest of fresh sweet corn. There are hundreds of sweet corn varieties from which to choose the ones to grow in your garden.
There are just a few simple rules to follow to grow a bumper crop of sweet corn. Site selection, soil nutrients and water are very important to grow a bounty of fresh corn on the cob. To begin, select a site on the north side of your garden. Corn plants are tall so that if planted on the east or west side, they will cast shadows on the other garden plants and decrease plant production. All vegetable plants need maximum sunlight.
There are two basic ways to plant sweet corn, in blocks or in hills. If space is not a problem, plant rows of corn in blocks of a minimum four rows, 2-½ to 3 feet apart. This is termed “block” planting; the rows can be as long as the gardener wants. For adequate pollination, sow all corn seed at the same planting. An alternative is to sow the corn in double rows in raised beds. If your soil is very poor, raised beds will be easier to establish, improve and maintain.
For small plantings of sweet corn, sowing in “hills” is sometimes recommended. Hills are groups of four to five seeds sown in a circle, with 2 inches between seeds. Space the hills 2 to 3 feet apart, and when the seedlings are established, thin each hill to two to three plants. For adequate pollination, a minimum of 12 – 24 plants are required.
Corn can be grown in large tubs (2 to 3 feet deep) for a patio container crop. Choose a large and deep container to be able to maintain soil moisture levels. Place the container in full sun or on a movable plant coaster to easily transport to a sunny location. Sow two or four seeds in clusters, 6 inches apart. Thin seedlings, choosing the most vigorous plants, keeping one plant for every 6 inches in the container. Maintain high nutrient levels and water frequently, as soil will probably dry quickly in the container. To insure proper pollination, shake the stalk allowing pollen to fall into the silks. Repeat the shaking process for several days while the pollen is maturing. Continue watering and fertilizing as the ears fill out.