Two weeks are left to plant sweet corn

A few weeks ago I wrote about planting your fall vegetable garden. This is the perfect time of the year to get the last of the summer vegetables in.

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One of the favorite crops that can be grown is sweet corn. Sweet corn can be grown both in the spring and fall. The last planting should happen in the next two weeks. This will depend on the variety that you are planting.

Sweet corn is one of the vegetables that needs a larger area to grow because of the size of the plants, but some people grow only 15 to 20 plants in their garden.

Sweet corn may be divided into three distinct types according to genetic background: normal sugary, sugary enhanced and supersweet.

There also are varieties now containing a combination of either two or all three of these genes, exhibiting qualities of each. Standard sweet corn varieties contain a "sugary gene" that is responsible for the sweetness and creamy texture of the kernels. These are best suited to being picked, husked and eaten within a very short time.

Sugary enhanced hybrids contain the sugary enhancer gene that significantly raises the sugar content above standard varieties while retaining the tenderness and creamy texture of standard varieties.

Some types of corn will cross with other varieties of corn. You can have yellow kernels on the same cob with white kernels. You can keep this from happening by isolating different varieties from each other. However, no isolation from standard varieties is necessary with these enhanced varieties.

The last type of sweet corn is supersweet hybrids. These varieties contain a gene which delays the conversion of sugar to starch, allowing them to stay sweet longer than other varieties.

The kernels of the supersweet varieties have a crispy, tough-skinned texture and contain low amounts of the water-soluble polysaccharides that impart the creamy texture and "corn" flavor to other sweet corn varieties.

Although the lack of creamy texture is not especially noticeable in fresh corn on the cob, it affects the quality of frozen and canned corn, as does the toughness of the seed coat. Supersweets should be isolated from any other type of corn tasseling at the same time to ensure sweetness and tenderness. Their pollen is weak and easily supplanted by other types, which causes the kernel to revert to a form with the toughness and starchiness of field corn. Because corn is wind-pollinated, this isolation distance should be 500 feet or more, especially downwind.

Many new varieties contain two or all three types of genes. These may be called by several different terms, including mixed gene, multi-gene, superior eating quality, sweet breeds and extra tender, among other names. All of these should be isolated in the same manner as the supersweet varieties.

Sweet corn does best when grown in a well-drained soil that has a pH of 6.0 to 6.5. It will grow in any soil type. The soil temperature in the spring of the year needs to be above 60 degrees before you plant your corn, but in the late summer you can plant anytime.

To properly prepare the soil, till it to a depth of 6 to 8 inches. The soil needs to have the right moisture. If it is too dry, you won't be able to till as deep, and if the soil is too wet it will form clods or hard clumps.

Corn is considered a heavy feeder. This means that it requires a great deal of fertilizer.

The best way to determine how much fertilizer to apply is to run a soil sample, which will show how much fertilizer and lime to apply. Fertilizer also should be applied two to three times when the corn is growing. The last application will be when the corn is around knee-high. This is called "side dressing," or what my grandfather called "laying by."

Sweet corn has very few disease problems. However, there are several insects that can damage corn. The most common is the corn ear worm. This is the caterpillar that you find when you shuck an ear of corn. The best way to control this insect is to use a product such as Dipel that contains Bt.

Sweet corn does take up a lot of space in the garden, but it can be worth it.

Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu. The extension Web address is www.ugaextension.com/columbia.