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Sweet Corn

Sweet Corn

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Estimated read time: 5-6 minutes

This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.

Larry Sagers Horticultural Specialist Utah State University Extension Service Thanksgiving Point Office © All Rights Reserved

Corn is found only found in cultivated environments. A wild grass, Teosinte (Zea mexicana) is the ancestor of all known species and grows wild in remote areas of Central America.

Native Americans throughout the Americas grew corn as a major food crop. The oldest known remains of corn are 7,000 years old. Credit Christopher Columbus with bringing corn or maize to Spain as he returned in 1493. It spread quickly, following the trade routes in the early 1500's.

Native Americans cultivated flint (or field) corn, sharing many different kinds with the colonists. In 1779, Papoon’ was the first recorded sweet corn variety obtained from Iroquois Indians. In 1821, a Connecticut seed company listed sugar corn in their catalog. Early Americans’ preferred white kernel corn to yellow, possibly because ‘Papoon’ was white.

James Vick’s Flower and Vegetable Garden Book, published in 1880 listed many sweet corn varieties. He described ‘Stowell’s Evergreen’ as: “Magnificent late variety, keeping in eating until frost.” ‘Stowell’s Evergreen’ was introduced in 1853 and ‘Country Gentleman’ introduced in 1890. Seed is still available for these old time varieties. Both have white kernels but the popularity of white corn changed in 1902 with the introduction of W. Atlee Burpee Company’s ‘Golden Bantam’, one of the most popular varieties ever.

The Connecticut Agricultural Experiment program released the first hybrid ‘Redgreen’ in 1924. ‘Golden Cross Bantam’, released by Purdue University in 1932 is still widely planted.

Scientifically, sweet corn is Zea mays regosa. The genus Zea, is Greek for some cereals, the species mays, a different spelling for maize, which means corn, and the variety regosa, means wrinkled and refers to the mature seed.

There are six major categories of corn. Gardeners are most interested in Zea mays regosa, or sweet corn. Other types are 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.

There are three types of sweet corn. They are normal sugary (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 shrunk 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.

Supersweet (sh2) types are excellent eating, but must be isolated from normal sugary and sugary enhanced sweet corn. The easiest ways to isolate varieties are to grow only one variety of sh2 sweet corn or grow varieties with maturity dates at least 10 14 days apart from the supersweet, so they will not release pollen simultaneously.

Planting instructions There are two ways to plant corn -- in blocks or in hills. 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 you want. In poor soil, raised beds are easier to establish, improve and maintain. Sow double rows on each raised bed.

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 24 plants are required.

For optimum growth and production, keep the patch weeded. Hoe or pull weeds until the stalks stand 12 to 15 inches tall. Avoid damaging the shallow root moisture and control weeds.

Sweet corn is a heavy feeder and quickly depletes soil nutrients. Use a complete fertilizer at planting and add nitrogen fertilizer when stalks are eight inches tall and when the tassels appear.

There are hundreds of sweet corn varieties to grow in your garden. Plant on the north side of the garden because corn plants are tall and will shade other garden plants.

Plant corn when soil gets warm. With soil temperatures of 58-68 degrees F, germination takes seven to 12 days; at 77- 95 degrees F, germination takes four to five days. Supersweet types do not germinate well in cool soils. Sow early, mid, and late season varieties at one time to stagger the harvest.

Planting recommendations:

Spacing: Plant corn in a block of several rows rather than a single row for better pollination and corn production. Sow seeds 3-6" apart in rows 2-3' apart. Use 1-3 ounces of seed per 100 ft. row.

Seed depth: Plant seeds 1" to 3" deep.

Planting date: Plant on average frost-free date, about May 10. For earlier production sow indoors in peat pots about 4 weeks early and transplant after frost danger is past. To prolong harvest, plant different varieties or same variety at 2-week intervals.

Environmental conditions:

Light: Full sun.

Temperature: 70-85øF. Matures faster in warmer weather.

Moisture: Needs steady, ample water supply during growing season. Increase watering during silking and kernel growth.

Fertilization: Band 1.5 lbs. all-purpose fertilizer (20-20-20) per 100 feet row at time of planting. Side dress fertilizer when plants are about 8" high with 1 cup of 34-0-0 for every 20 ft. of row.

Recommended varieties:

Normal Sugar: Earlivee, Golden Earlipack, Jubilee

Super Sweet: (Should be isolated to insure optimal flavor) Yellow: Super Sweet Jubilee, Sweetie White: How Sweet It Is Bicolor: Phenomenal

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.

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