Corn falls into six major categories. Gardeners are most interested in Zea mays regosa, or sweet corn. Other types include popcorn that explodes when heated and genetic dwarf or midget corn with mature ears at four to six inches in length. Broom corn, is grown for the long fibrous tassels used for making brooms or dried arrangements. Field corn is dent corn because of the hollow space on the top of dried kernels. Dent corn is used for animal feed, oil and sweeteners. The last category is decorative, multicolored Flint or Indian corn. Corn remains one of the world's three most important cereal crops for human and domestic animal consumption.
Gardeners grow three types of sweet corn and ornamental corn:
Sweet corns include sugar (su), sugary enhanced (se) and supersweet (sh2). These types refer to the sugar content and sweet flavor in the kernels when mature. The normal sugary (su) sweet corn converts kernel sugar to starch immediately after harvest. This means the sweet flavor is lost rapidly.
Supersweet types were discovered in 1950. They contain more sugar and when dried, the kernels shrank -- thus the name "shrunken two" (sh2). These high sugar types are 'Supersweet' because the sugar level can be twice as great as normal sugary (su) sweet corn at maturity. The supersweet types converts sugar to starch slower so the sweet flavor lasts longer after harvest.
Ten years later a new type, sugary enhanced (se) genetic type corn was introduced. The (se) corn has higher sugar levels so the sweet flavor lasts longer after harvest. These (se) sugary enhanced types are very popular because they combine sweet flavor with easy growing needs.
While ornamentals come in multiple colors, other categories include both white and yellow kerneled varieties.
Normal Sugar: Earlivee, Golden Earlipack, Jubilee
Super Sweet: (Should be isolated to insure optimal flavor)
Yellow: Super Sweet Jubilee,
White: How Sweet It Is
Sugary Enhanced: (Best series for flavor)
Yellow: Honey Buns, Incredible, Miracle, Precocious
White: Platinum Lady
Bicolor: Double Delight, Breeder's Choice, Honey & Pearls
Ornamental: Calico Indian or Squaw Corn, Cutie Blues.
Seed Viability (Years)
1 - 2 years
Air Temp: 70-75° F daytime and 60° to 65° nighttime. Soil temperatures for sweet corn: 58-68° F Soil temperatures for super-sweet corns: 77-95° F.
Soil Temperatures/Days 58° to 65° F: 7 to 12 days 50° F: 22 days 59° F: 12 days 68° F: 7 days 77° F to 86° F: 4 days 95° F: 3 days
There are two ways to plant corn -- in blocks or in hills. Plant corn in a block of several rows rather than a single row for better pollination and ear production.
Rows: if space is adequate, plant rows of corn in blocks of a minimum of four rows, 2 1/2 to 3 feet apart. Block planting insures adequate pollination and the rows can be as long as desired.
Raised Beds: in poor soil, raised beds are easier to establish, improve and maintain. Sow double rows on each raised bed. Plant at least four rows total (two raised beds) side by side, for adequate pollination.
Hills: for small plantings, sow corn in hills. Hills are groups of 4 to 5 seeds sown in a circle, with 2 inches between seeds. Space the hills 2 to 3 feet apart and when seedlings emerge, thin each hill to 2 to 3 plants. For adequate pollination, 12 to 24 plants are required.
Corn should be planted after the last frost. For earlier production, corn can be sown indoors in peat pots about 4 weeks early and transplanted after the frost danger is past.
Corn can be planted outdoors when air temperatures reach 70-85°F. Soil should be at least 58-68°F or wait until it reaches at 77- 95°F for supersweet types. Supersweet types do not germinate well in cool soils.