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ZEA mays var. rugosa

Image of Zea mays var. rugosa

Doug Wilson, USDA/ARS



Botanical Name

ZEA mays var. rugosa

Plant Common Name

Sweet Corn

General Description

Sweet corn arose as a mutation of standard field corn. The kernels of this summer favorite have a higher sugar content and the ears are harvested when young and tender, unlike hard corn varieties. Several Native American tribes grew sweet corn, but records suggest it was the Iroquois who first introduced it to European settlers in 1779.

As one of the key grains that feed the world today, corn is a vitally important plant. It also has an interesting history. Oddly enough, it does not exist in the wild, and research supports that it is truly the result of human innovation. Modern corn has been traced back to the wild Central American grass, teosinte (Zea mays ssp. parviglumis), which does not resemble cultivated corn. It is believed that over 2000 years mutants of this primitive maize were discovered, selected and cultivated by North American natives. The first explorers brought corn to Europe and Africa where it quickly gained popularity.

Corn is a warm season annual garden vegetable. In the tropics, it is grown in fall and winter. The tall grassy plants will take off as soon as days and nights lose their chill. They develop tall stalks with long, thick arching green blades. Each stalk has two flower types; the pollen-producing male tassels and the ears of seed-producing female flowers. The tassels shed windborne pollen grains which pollinate the distinctive silky hair-like styles that protrude from the tips of the ears. Juicy sweet kernels develop following pollination. Ears are not receptive to pollen from the same stalk, so several rows of each variety must be planted to insure cross pollination. Sweet corn should be protected from cross pollination with hard corn types, such as field, pop or flint, because it can reduce sweetness. Sweet corn cultivars are ranked by sugar levels: normal sugar (SU), enhanced sugar (SE) and super sweet (Sh2).

This corn is harvested in mid to late summer and there are many varieties with white, yellow or peach-colored kernels. Bicolors are not uncommon. Days to harvest vary from 65 to 90 days. It is essential to pick corn at its prime and store it properly. An ear is ready when the kernels are full, plump and properly colored. Another test is to pierce a plump kernel with your nail. If it emits milky juice, it is ready. When buying fresh corn at the store, you can always tell the freshest ears because these will have new white cuts at the base of the ear. Those with brown bases should be avoided because corn tends to get starchy and loses its sweetness with age.

Grow corn in full hot sun and fertile, nutrient-rich soil with good drainage. It grows best with intermittent watering. There are a number of diseases and pests that plague corn. Corn earworms are common as are nighttime raids from raccoons. The grotesque fungal disease called corn smut is another problem to be watchful of.

Sweet corn is a must for the large warm season veggie garden. There are lots of wonderful varieties to choose from and nothing makes the summer sweeter or tastier.


  • AHS Heat Zone

    12 - 4

  • Sunset Zone

    A1, A2, A3, H1, H2, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type


  • Sun Exposure

    Full Sun

  • Height

    6'-8' / 1.8m - 2.4m

  • Width

    2'-4' / 0.6m - 1.2m

  • Bloom Time


  • Native To

    Hybrid Origin, North America, Central America, South America

Growing Conditions

  • Soil pH


  • Soil Drainage

    Well Drained

  • Soil type

    Clay, Loam, Sand

  • Growth Rate

    Very Fast

  • Water Requirements

    Average Water

  • Habit


  • Seasonal Interest

    Spring, Summer, Fall, Winter

Ornamental Features

  • Flower Interest


  • Fruit Color

    White, Yellow, Light Yellow, Peach

  • Foliage Color (Spring)

    Green, Dark Green

  • Foliage Color (Summer)

    Green, Dark Green

  • Foliage Color (Fall)

    Green, Dark Green

  • Foliage Color (Winter)

    Green, Dark Green

  • Fragrant Flowers


  • Fragrant Fruit


  • Fragrant Foliage


  • Bark or Stem Fragrant


  • Repeat Bloomer


  • Showy Fruit


  • Edible Fruit


  • Showy Foliage


  • Foliage Texture


  • Foliage Sheen


  • Evergreen


  • Showy Bark


Special Characteristics

  • Usage

    Edible, Herb / Vegetable

  • Sharp or Has Thorns


  • Invasive


  • Self-Sowing