Sweet corn (Zea mays L. var. rugosa )-Hort Answers - University of Illinois Extension
University of Illinois Extension

University of Illinois Extension

Hort Answers


Sweet corn
Zea mays L. var. rugosa


Sweet corn is a warm-season vegetable that can be grown easily in any garden with sufficient light, fertility, growing season and space. It is especially popular with home gardeners because it tastes appreciably better when it is harvested and eaten fresh from the garden. Successive plantings can yield continual harvests from early summer until frost if the weather cooperates. Sweet corn may be divided into three distinct types according to genetic background: normal sugary (SU), sugary enhancer (SE) and supersweet (Sh2).

Standard sweet corn varieties contain a "sugary (SU) gene" that is responsible for the sweetness and creamy texture of the kernels. SUs are best suited to being picked, husked and eaten within a very short time. In the home garden, this is sometimes possible but not always practical. The old adage was "start the water boiling, run to the patch, pick and husk the corn, run back to the pot, cook the corn, and eat or process immediately." Sugary enhancer hybrids contain the sugary enhancer (SE) gene, that significantly raises the sugar content above standard SUs while retaining the tenderness and creamy texture of standard varieties. The taste, tenderness and texture are outstanding. SEs are the gourmet corns of choice for home gardeners because they contain the best qualities of both SU and Sh2 types. Fresh from the garden, virtually all current SE releases have eating quality that is superior to all other types. No isolation from standard SUs is necessary. Supersweet hybrids contain the shrunken -2 gene and have a higher sugar content than the standard SU varieties. The kernels of the extra-sweet varieties have a crispy, tough-skinned texture and contain low amounts of the water-soluble polysaccharides that impart the creamy texture and "corny" 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, SEs are superior in eating quality to Sh2s.

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 can be 500 feet or more, especially downwind.

Cultivate shallowly to control weeds. Chemical herbicides are not recommended for home gardens. Although corn is a warm-weather crop, lack of water at critical periods can seriously reduce quality and yield. If rainfall is deficient, irrigate thoroughly during emergence of the tassels, silking and maturation of the ears. Hot, droughty conditions during pollination result in missing kernels, small ears and poor development of the tips of the ears. Side-dress nitrogen fertilizer when the plants are 12 to 18 inches tall. Some sweet corn varieties produce more side shoots or "suckers" than others. Removing these side shoots is time consuming and does not improve yields. Sweet corn requires warm soil for germination (above 55 F for standard sweet corn varieties and about 65 F for supersweet varieties). Early plantings of standard sweet corn should be made at, or just before, the mean frost-free date unless you use special soil-warming protection such as clear polyethylene mulch film. For a continuous supply of sweet corn throughout the summer, plant an early variety, a second early variety and a main-crop variety in the first planting. For example, you may wish to select Sundance (69 days) for the first early variety, Tuxedo (75 days) for the second early variety and Incredible (83 days) for the main-crop variety. Make a second planting and successive plantings of your favorite main-crop or late variety when three to four leaves have appeared on the seedlings in the previous planting. Plantings can be made as late as the first week of July.


Most of the varieties listed here (like nearly all sweet corn sold today) are hybrids. They are arranged by genetic type and kernel color. The maturity dates are relative because the actual number of days to harvest varies from year to year and location to location.

Standard (SU) varieties (days to harvest, ear size, and comments):

  • Yellow: Earlivee (58 days; 7"-14 rows; extra early), Golden Cross Bantam (85 days; 8"-12 to 14 rows; old home-garden variety), Iochief (86 days; 8"-14 to 16 rows; popular midseason variety), Jubilee (82 days; 8"-16 rows; high yield; deep, narrow kernels; excellent for canning), NK-199 (84 days; 8"-18 to 20 rows; extremely thick, attractive ears; silks easily removed), Seneca Horizon (65 days; 7"-16 to 18 rows; excellent quality), Sundance (69 days; 1/2"-14 rows; cold-soil tolerance, early season vigor; handsome ears)
  • White: Pearl White (75 days; 7 to 8"-12 to 16 rows; good; cool-soil and drought tolerance; easy snapping), Platinum Lady (86 days; 8 1/2"-14 rows; tender kernels; slender, elegant ears), Silver Queen (92 days; 8 to 9"-14 to 16 rows; dark green flag leaves; attractive ears; standard, high-quality white corn; resistant to bacterial wilt and Helminthosporium)
  • Bicolor: BiQueen (92 days; 8 to 9"-16 rows),Butter & Sugar(75 days; 7"-14 rows; popular for home garden), Honey & Cream (80 days; 7"-12 to 14 rows; sweet, tender; long, tight husks), Quickie (64 days; 7 1/2"-12 rows; earliest SU bicolor), Sugar & Gold (67 days; 6 1/2"-10 to 12 rows; husk green, with reddish tinge; excellent quality; prefers cooler-season areas)

Sugary Extender (SE) varieties (days to harvest, ear size, and comments):

  • Bodacious (72 days; 8"-16 to 18 rows; superior flavor, holding ability; ears snap easily; prefers warm soil), Champ 68 (days; 8"-16 to 18 rows; excellent eating quality, and tip cover), Incredible (83 days; 8 to 9"-18 rows; big, flavorful ears; excellent appearance, yield), Kandy Korn (89 days; 8"-14 to 16 rows; purplish red-streaked ear flags, excellent quality, long shelf life), Maple Sweet (70 days; 7 1/2"-14 to 16 rows; excellent flavor, easy snapping), Merlin (84 days; 9"-20 to 22 rows; superior flavor, ear size, disease tolerance; easy snapping), Miracle (84 days; 9 1/2"-16 to 18 rows; good holding quality; large, tender, attractive, tasty ears), Precocious (66 days; 7"-12 to 14 rows; very early; excellent eating, good tipfill), Spring Treat (67 days; 7"-14 rows; easy snapping, straight rows of kernels), Sugar Buns (72 days; 7 1/2"-14 rows; excellent flavor; attractive, relatively small ears; deep kernels), Terminator (83 days; 9"-20 rows; large ears, superior disease resistance), Tuxedo (75 days; 7 1/2"-16 to 20 rows; excellent early vigor; good tipfill, husk cover; excellent eating quality; tolerant to Stewart's wilt, and smut)
  • White: Alpine (79 days; 8"-16 rows; widely adapted; excellent yield; cool-soil tolerance; attractive ear), Argent (86 days 8 to 9"-16 rows; good cold-soil vigor; tolerant to Stewart's wilt), Incredible Avalanche (78 days; 8"-16 rows; excellent eating; good ear appearance), Cotton Candy (72 days; 7 to 8"-16 to 18 rows;extended harvest; reddish green stalks), Divinity (78 days; 8"-16 rows; excellent flavor, tenderness; snow white color; excellent tip cover; tolerant to drought, Stewart's wilt), Pristine (76 days; 8 to 9"-16 rows; terrific eating quality, tolerant to Stewart's wilt), Seneca Starshine (71 days; 7 to 8"-16 rows; blocky ears, with pure white kernels; excellent tenderness, flavor, appearance; prefers 50 ?F or higher soil temperature for germination), Seneca White Knight (74 days; 8 to 9"-16 rows; high quality; attractive ears; great taste), Snowbelle (79 days; 7 to 8"-14 to 16 rows; creamy texture; pretty, compact ears), Spring Snow (65 days; 7 to 8"-12 rows; excellent husk cover; very early; attractive ears; very tender kernels; compact plant), Sugar Snow (71 days; 8 to 9"-16 rows; extremely sweet, snow white kernels; good cold-soil tolerance), Telstar (79 days; 8"-16 rows; vigorous; dark green flag leaves; tasty; attractive ear), Ambrosia (75 days; 8"-16 rows; good spring vigor; fairly large, tasty ears; tolerant to Stewart's wilt), Calico Belle (79 days; 8"-16 to 18 rows; high yield; attractive; delicious taste; good disease tolerance), D'Artagnan (71 days; 8"-16 rows; superior quality in an early SE bicolor), Diamonds & Gold (79 days; 8"-18 rows; sweet, tender; good tipfill; attractive dark green ears), Double Delight (85 days; 9"-16 rows; large, tasty ears; dark green husk; like a bicolor), Incredible Double Gem (74 days; 8 to 9"-16 to 18 rows; excellent eating quality; blocky ears; usually double ears on stalks) Kiss 'N Tell (68 days; 7 to 8"-14 to 16 rows; two ears per stalk; good tipfill), Lancelot (80 days; 8"-16 to 18 rows; vigorous, stress-tolerant plant; good yields; high quality ears under adverse conditions), Medley (73 days; 8"-16 rows; dark green flags; good tip cover; tolerant to Stewart's wilt), Peaches & Cream (83 days; 8"-16 to 18 rows; tasty, poplar home-garden variety; vigorous plant; good ear protection), Seneca Brave (73 days; 8"-18 to 20 rows; husky, excellent quality ears; strong plants), Seneca Dawn (69 days; 7 to 8"-14 to 16 rows; excellent early bicolor; good vigor, eating quality)

Supersweet (Sh2) varieties (days to harvest, ear size, and comments):

  • Yellow: Crisp 'N Sweet (85 days; 9"-18 rows; high yield; excellent disease resistance; good germination, seedling vigor), Early Xtra Sweet (70 days; 8"-16 rows; like the original, but earlier), Excel (82 days; 8 1/2" - 16 rows; exceptionally high yield, easy to harvest), Illini Gold (79 days; 8 1/2"-16 rows; midseason supersweet), Illini Xtra Sweet (85 days; 8"-14 to 16 rows), Jubilee Supersweet (83 days; 9"-18 rows; excellent home garden supersweet), Showcase (83 days; 8" large ear on short plant, outstanding eating quality)
  • White: Aspen (83 days; 8 to 9"-16 rows; large, attractive ears; high eating quality), Camelot (86 days; 8"-18 to 20 rows; clean, sturdy plants; excellent quality, holding traits), How Sweet It Is (85 days; 8"-16 rows; All-America Selection winner, sensitive to cold soil, holds quality well), Pegasus (85 days; 8 1/2"-18 rows; good cold soil germination, vigor), Treasure (83 days 8 1/2"-18 rows; good vigor, seedling emergence)
  • Bicolor: (Aloha 82 days; 9"-16 rows; excellent appearance), Dazzle (82 days; 8"-16 to 18 rows; good looking ear; good disease resistance; creamy texture), Honey 'N Pearl (78 days; 8 1/2"-16 rows; 1988 All-America Selection winner, stands well, excellent quality), Hudson (83 days; 8"-18 rows smooth, well-filled ears; superior eating quality, tenderness), Phenomenal (85 days; 8 1/2"-16 rows; excellent eating quality, beautiful ears), Radiance (73 days; 8"-16 to 18 rows; excellent seedling emergence, plant vigor).

Open-Pollinated (SU) varieties (days to harvest, ear size, and comments):

  • Yellow: Ashworth (69 days; 6 to 7" ears, 12 rows; good cold soil germination; good flavor for an early type), Golden Bantam (82 days; 6 to 7"ears, 10 to 14 rows rich corn flavor, sweet, tender)
  • White: Country Gentleman (96 days; 7" ears, kernels not in rows very tender, shoe-peg type; drought resistant), Stowell's Evergreen (100 days; 9"ears, 18 to 20 rows; big, juicy, white kernels; ripen over long period), Trucker's Favorite (95 days; 8 to 9" ears, 14 rows; delicious white kernels, high yields)
  • Bicolor: Double Standard (73 days; 7"ears, 12 to 14 rows; first bicolor open-pollinated type; good cold soil germination, good flavor, tenderness; traditional corn taste)
  • Black: Black Aztec (75 days; 7"ears, 8 to 10 rows; vigorous drought tolerant; sweet white kernels in roasting ear stage, dark blue-black at maturity; good for blue corn meal).
Planting Time
Sweet corn need to be planted at about the average frost-free date. Sweet corn germinates when soil temperature is above 55 degrees F and some extra-sweet varieties germinate when soil temperature is about 65 degrees F.


Harvest Time
Under good growing conditions (correct spacing; freedom from weeds, insects and disease; and adequate moisture and fertility), many varieties produce a second ear. This second ear is usually smaller and develops later than the first ear. Each cornstalk should produce at least one large ear.


Plant the kernels (seeds) 1/2 inch deep in cool, moist soils and one to one and a half inches deep in warm, dry soils. Space the kernels 9 to 12 inches apart in the row. Plant two or more rows of each variety side by side to ensure good pollination and ear development. Allow 30 to 36 inches between rows.


Soil Conditions
Moist, Well-Drained
Exposure/Light Requirements
Full Sun
Pests and Problems

Environmental Damage

Fungal Disease

Herbicide Injury

Insect Damage

Additional pests and problems that may affect this plant:

Insect pests:

  • Seed corn maggot
  • Wireworm
  • Flea beetle
  • European corn borer
  • Corn ear worm
  • Fall armyworm
  • Corn root worm


  • Crazy top (Sclerophthora macrospora)
  • Gray leaf spot (Cercospora zea-maydis)
  • Stewart's bacterial wilt (Erwinia stewartii)
  • Smut (Ustilago maydis)
  • Viral Diseases: Maize dwarf mosaic, Maize chlorotic dward, Wheat streak mosic, Maize streak
Additional Notes

All sweet corn should be protected from possible cross-pollination by other types of corn (field, pop or flint). If you plant supersweet or synergistic sweet corn varieties, plan your garden arrangement and planting schedule so as to prevent cross-pollination between these varieties and with any other corn, including nonSh2 sweet corns. Supersweet varieties pollinated by standard sweet corn, popcorn or field corn do not develop a high sugar content and are starchy. Cross-pollination between yellow and white sweet corn varieties of the same type affects only the appearance of the white corn, not the eating quality.


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