Sweet Corn Plant Profile

A traditional summer treat

Shucking and ear of corn

Peter Dazeley/Getty Images

In This Article

Corn is one of the most popular vegetables to grow and eat, and it's all the more delicious when freshly harvested. It's also surprisingly easy to grow your own. Corn grows from tall, straight stalks that produce husked ears of tender kernels tufted with silks. Most corn varieties look alike on the outside, but under the husks, sweet corn can be white, yellow, bicolor, or even red. Many modern sweet corn varieties have been bred to mature early in the season, but later-maturing types tend to be sweeter.

Sweet corn is an annual that is planted in spring and grows through the summer. It is ready to harvest about three months after planting, but early varieties can be ready in as little as two months.

Botanical Name Zea mays
Common Name Sweet corn
Plant Type Annual
Mature Size 6 to 8 feet tall, 1 to 2 feet wide
Sun Exposure Full sun
Soil Type Loamy
Soil pH Acidic to Neutral (6.0 to 7.0)
Bloom Time Summer
Flower Color Yellow
Hardiness Zones 2 to 11 (USDA)
Native Area Mexico
Toxicity Non-toxic
corn field
The Spruce / Autumn Wood 
ears of corn growing
The Spruce / Autumn Wood  
closeup of an ear of corn
The Spruce / Autumn Wood 

How to Plant Sweet Corn

Sweet corn does not transplant well from seedlings unless you are using a biodegradable pot. The best way to plant sweet corn is to direct-seed after any danger of frost has passed. Because corn is pollinated by the wind, it does best when planted in blocks rather than rows. Pollen from the male tassels needs to make contact with the female silks, and close planting means more contact. Wind pollination also results in easy cross-pollination, so keep different types of corn separated by at least 25 feet or plant varieties that mature at different times. Plant the seeds 1 1/2 to 2 inches deep with a spacing of 4 to 6 inches, and give the seeds a good watering.

The size of your corn plants will vary with the type of corn you are growing and the growing conditions, but most corn plants average between 6 and 8 feet tall. There are shorter varieties for gardens with limited space.

Although it is easy enough to grow corn in any warm, sunny garden, it is often difficult to successfully bring the fruit to harvest because of the competition from crows, raccoons, squirrels, and other pests who find corn as delicious as you do. Traditional wisdom says harvest your corn the day before the raccoons do.

Sweet Corn Care

Light

To grow well and have the ears fill out, your corn will need a spot that gets full sun.

Soil

The soil should be loose and loamy, with a neutral pH of 6.0 to 7.0. Heavy soils inhibit corn's long taproots. The shallow roots that form on the soil surface are predominantly there to anchor the tall plants.

Water

Water regularly, especially if you notice the leaves curling and when the cobs begin to swell. It is better to water deeply once a week, rather than providing a little water daily. Keep the area free of weeds that will compete for food and water.

Temperature and Humidity

Soil temperature should range between 60 and 65 degrees Fahrenheit. Otherwise, corn seeds will not germinate properly. In colder climates, you can cover the soil with black plastic beforehand to help warm the soil more quickly.

Fertilizer

Corn is a heavy feeder, requiring rich soil. Nitrogen is especially important since corn is basically a grass. An inch or two of compost or rotted manure will also work, as will feeding with fish emulsion. Apply nitrogen fertilizer once the plants are about 8 inches tall and again when they start producing tassels.

Sweet Corn Varieties

There are hundreds of corn varieties today, virtually all falling under six major categories: sweet corn, popcorn, corn for animal feed, dwarf corn, decorative corn, and multicolored Indian corn. Some of the most popular cultivars for growing sweet corn include:

  • 'Early Sunglow': Early and sweet; good for shorter seasons and small gardens
  • 'Silver Queen': Another early producer with pale white kernels; highly disease-resistant
  • 'Golden Bantam': An open-pollinated heirloom variety, often called the original sweet corn
  • 'Tuxedo': A "supersweet" variety with extra-long ears

Harvesting

Each stalk of sweet corn should produce at least one ear of corn. Pick corn when you see fat, dark green ears with brown tassels. Squeeze to test for firmness and a rounded, not pointed tip. Finally, pierce a kernel with a fingernail. If it spurts milky liquid, it is ready. Pull the ears downward and twist to take the cob off the stalk. Be prepared to eat or preserve sweet corn immediately after picking—sweetness fades soon after harvesting. Sweet corn freezes well, though, whether or not you remove the kernels from the husks before freezing.

Common Pests and Diseases

Animals will be the biggest pest problem. Corn borers can be kept in check with an organic pesticide such as Bt (Bacillus thuringiensis), and by destroying the stalks at the end of the season. Flea beetles spread bacterial wilt. Combat them by planting resistant varieties.

Be on the lookout for a grayish-black fungus called smut. Although some cultures find it a delicious treat, it can kill your corn harvest. Remove and destroy the fungus while young, before the mass bursts and sends the spores everywhere.