Corn delivers the sweet taste of sunshine

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Last Updated: 
July 12, 2006

CORVALLIS - Sweet corn just seems to be getting sweeter.

Besides the "standard" sweet corn varieties, there are also supersweet and sugar-enhanced types. In fact, there are dozens of varieties of sweet corn to choose from, with each offering a different combination of sweetness, texture, kernel color, maturity date and disease resistance, according to Jan McNeilan, consumer horticulture agent with the Oregon State University Extension Service.

Standard sweet corn contain a "sugary gene" responsible for the kernels' sweetness and creamy texture. The supersweets are sweeter than standard or sugar enhanced varieties. They have up to three times the sugar content initially and convert sugar to starch more slowly, preserving the sweetness for a longer time than standard varieties. Supersweets have crispier kernels and contain fewer complex sugars, so are less creamy than the other types.

And there is corn color to consider. Yellow, white or bicolor is mostly a matter of personal preference. However, yellow corn has the nutritional advantage of being a fairly good source of vitamin A; white corn contains virtually no vitamin A.

When purchasing corn seed, pay attention to days to maturity and whether a variety is "early," "main" or "late" season. For a continuous supply of corn, plant early varieties and late varieties in your first planting. Make your subsequent plantings using main-season varieties, after the previous planting emerges.

Since sweet corn is wind-pollinated, the plants should be in three or more short rows rather than one long row. To minimize cross-pollination, supersweet types must be isolated from the standard sweets. Either plant these varieties two weeks after the standard sweets have emerged, or separate supersweets from standard sweets by at least 250 feet. Or better still, plant only one type-all supersweet or all standard sweet.

Popcorn and field corn have genes that are dominant over sweet corn. If planted too close, the sweet corn will be tough and starchy.

Sweet corn thrives in the warmth of summer, with plenty of sunlight, water and nutrients. Plant corn from early May through June in most parts of the state. The soil should be 55 degrees for germination of standard varieties and 65 degrees for the supersweet varieties.

Corn has a high nitrogen requirement, so enrich the soil before planting, working fertilizer into the soil three to four inches deep. After the plants are up, thin them six to nine inches apart. Too many seedlings have the same effect as too many weeds. Crowded corn will have small, poorly filled ears.

Adequate soil moisture is critical especially when silk and kernels are forming. However, avoid waterlogged, poorly drained soils because root decay may occur.

OSU-recommended standard yellow varieties for Oregon include:

Yellow Kernels

  • Standard sweet (early): Sundance, Early Sunglow.
    (main season): Jubilee (also called Golden Jubilee).
  • Supersweet (early): Butterfruit.
    (main season): Supersweet Jubilee.
  • Sugary enhanced (very early): Sugar Buns.
    (early): Precocious, Kandy Kwik.
    (main season): Incredible, Kandy King, Kandy Korn, Legend, Bodacious.

White Kernels (must be isolated from yellow or bicolor types to get all white kernels)


  • Supersweet (early): Sweet Magic.
    (main season): How Sweet It Is, Seneca Sugarburst.
  • Sugary enhanced (main season): Silverado, Argent, Frosty, Sugar Snow II, Brilliance.

Bicolor Kernels

  • Supersweet (early): Top Notch.
    (main season): Honey and Pearl, Phenomenal, Candy Corner.
  • Sugary enhanced (early): Native Gem, Trinity.
    (main season): Temptation, Double Gem, Double Choice.
  • Triple Sweet types (sh2su hybrids): Sweet Rhythm, Serendipity, Sugar Ace.

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Author: Peg Herring
Source: Jan McNeilan