Issue: May 2005

Sweeten Meals with Homegrown Sweet Corn

Corn-loving gardeners have many sweet corn varieties to choose from, but they should pick carefully for maximum sweetness.

Sweet corn varieties are available in yellow, white or bicolored types that vary in maturity dates from early to late season. Weather will also affect maturity dates.

Sweet corns are classified into four different groups based on kernel sweetness. Traditional or standard sweet corn varieties contain moderate amounts of sugar that is rapidly converted to starch after harvest, particularly if it's not refrigerated. The amount of sugar varies with variety.

"Super sweet" corns contain a shrunken gene that produces sucrose levels two to three times higher than standard sweet corn varieties. Relatively small amounts of sugar convert to starch after harvest, but super sweets will become starchy and tough if pollinated by standard sweet corn varieties. To protect super sweet varieties from other standard sweet corns, plant them at least 25 feet away or vary the maturity dates to stagger the harvest.

Super sweets grow best when soil temperatures are 60°F or higher. Plant seeds at shallow depths of three-fourths to one inch. For best quality, refrigerate immediately after harvest.

"Sugar enhanced" sweet corn varieties retain sweetness with genes that slow kernel conversion of sugar to starch after harvest. The result is greater tenderness and varying degrees of sweetness. These varieties do not have to be isolated from traditional or standard varieties of sweet corn.

With "synergistic" sweet corn varieties, kernels contain 75 percent standard sweet genes and 25 percent super sweet, resulting in relatively tender kernels that are very sweet. Allow ears to fully mature to avoid watery texture.

Plant sweet corn in rows 30 to 36 inches apart. Space plants 6 to 10 inches apart. Plant in blocks of four or more rows for good pollination. Apply phosphorus fertilizer before planting and incorporate it into the soil. Apply nitrogen fertilizers in split applications before and after plants emerge. Determine fertilizer requirements with a soil analysis before planting.

Harvest ears when kernels are full and milky. Generally, this occurs when silk begins to turn brown and dry, or about 18 to 24 days after silk appears. The warmer the weather, the sooner ears will mature.

For more information on growing sweet corn, see Guide H-223, Home and Market Garden Sweet Corn Production. For a free copy of the guide, or for more gardening information, visit New Mexico State University's Cooperative Extension Service publications world wide web site at http://pubs.nmsu.edu/_h.

George W. Dickerson, Ph.D., is is a horticulturist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

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