Sweet Corn
There is nothing better than a fresh ear of sweet corn on an early summer evening or maybe for breakfast for that matter. Around my house we love sweet corn, so I hope the information in this article will help you grow a bumper crop this year.
The most important factor is the variety that you choose to plant. This will determine the sweetness, crispness and shelf-life of your sweet corn. Sweet corn may be divided into three distinct types according to genetic background: normal sugary (su), sugary enhanced (se) and supersweet (sh2). There are also varieties now containing a combination of genes, exhibiting qualities of each.
Standard sweet corn varieties contain a “sugary (su) gene” that is responsible for the sweetness and creamy texture of the kernels. Su’s are best suited to being picked, husked and eaten within a very short time. Silver Queen is an example of a standard sweet corn variety.
Sugary enhanced hybrids contain the sugary enhancer (se) gene that significantly raises the sugar content above standard varieties while retaining the tenderness and creamy texture of standard varieties. No isolation from standard varieties is necessary. Silver King is a sugary enhanced variety.
Supersweet hybrids contain the shrunken (sh2) gene, which delays the conversion of sugar to starch, allowing them to stay sweet longer than su 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. Unless corn must be stored, shipped or mechanically harvested, se’s are superior in eating quality to sh2’s.
Supersweets (sh2) 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 sh2 varieties.
Sweet corn germinates best when soil temps are above 60⁰F, and need a soil pH between 6.0 and 6.5. Seed should be planted at least 1” deep and about every 8-12” in the row. As stated above corn is wind pollinated so it is better to have multiple short rows rather than one long row. Separation of different varieties can be by distance or by planting (tasseling) date.
Water is critical for a successful sweet corn crop. It is important to realize the ear and kernels are beginning to form at about the 6 leaf stage of growth, and continue to just before silking. Any stress due to insects or drought can significantly decrease ear size and kernel numbers. I am sure that most gardeners have picked an ear of corn that has had missing kernels or zippering. This is most likely the result of stress during the ear development. So if you want to enjoy some sweet gold this summer, follow these recommendations and fertilize according to your soil sample. As always contact your County Agent if you have any questions.
