Growing sweet corn requires space, planning

Richard Bogren, Gill, Daniel J.

For Release On Or After 03/12/10

By Dan Gill
LSU AgCenter Horticulturist

Perk up your ears… of sweet corn, that is. Corn harvested from the home garden and cooked within minutes is considered one of life’s great treats by those lucky enough to have enjoyed it – and now is the time to plant it.

Corn plants are fairly large, and they occupy a goodly amount of space in the garden. As a result, many vegetable gardeners don’t plant corn, especially if they have a small space. But if you have the space, growing sweet corn is not that much of a challenge. And the results are delicious.

Types to grow

Sweet corn is harvested over a relatively short period because all of the ears ripen at about the same time. You can get around this by planting varieties that ripen at different times. Sweet corn varieties are grouped by how long it takes from planting to harvest. Recommendations for Louisiana include:

– Early-maturing: Seneca Horizon and Aztec.

– Mid-season: Bonanza, Merit and Funks Sweet G90 (bi-color).

– Late-maturing: Silver Queen (white), NK199, Iochief, Gold Queen and Golden Cross Bantam.

If you prefer, you can plant the same variety in successive plantings to stretch out its season. When you do this, plant seeds in one area and then plant seeds in another area two or three weeks later.

You also can find extra-sweet sweet corn varieties. They contain more sugar than normal sweet corn and are able to hold their sugar levels longer after harvest. Based on the genetics involved, they are grouped into two categories – supersweet and sugary enhanced.

Recommended supersweet types – which must be isolated from other varieties to prevent cross pollination – include Prime Plus Y, Promise Y, How Sweet It Is, Honey-N-Pearl and Pegasus.

Sugary enhanced types recommended for Louisiana include Honey Select, Accord, Miracle, Argent, Merlin, Summer Flavor, AmbrosiaBC and Calico BelleBC.


Planting corn early – now through mid April – reduces problems with corn earworms, the leading insect pest of corn in the home garden. Generally, when planted this month, corn may not require any pesticide sprays at all.

Although sweet corn does require room, a 4-by-8-foot raised bed can accommodate two rows of corn with the plants in each row spaced 10 inches apart. That’s 20 plants. If they each produce two ears, you have a generous harvest of 40 ears of corn.

Prepare the ground for planting corn by first removing any weeds or unwanted vegetation. Turn the soil to a depth of a shovel blade (about 8 inches), apply a 2- to 3-inch layer of compost or composted manure and a general purpose fertilizer following package directions, and thoroughly mix everything together.

When planting sweet corn, plant two or three seeds every 10 inches in the row and bury them about one-half to 1 inch deep. Then water thoroughly. After the seeds germinate and the plants are 3-4 inches tall, thin to one plant per 10 inches.

Sidedress with a nitrogen-containing fertilizer when the plants are about 12 inches high and again when the plants are 24 to 36 inches high. Corn is a heavy feeder.

Pollination issues

Corn is wind pollinated. The male flowers that shed the pollen are located at the top of the plant in the tassel. The female flowers are arranged in rows along the cob enclosed by the shucks. A silk is connected to each of the female flowers, and the other ends of the silks hang outside the shuck. At least one pollen grain must land on each silk to pollinate a female flower, which produces one kernel of corn.

Each kernel of corn is the result of a separate act of pollination. So, it is important to plant corn properly to make sure the wind deposits the pollen on the silks.

By planting sweet corn in a block of several short rows side by side rather than one or two long rows, you allow the pollen to move from one plant to another more surely no matter which way the wind is blowing. Poorly filled-out ears is generally the result of poor pollination.

Harvest and use

The best time to harvest sweet corn is in early morning while the temperature is low. To determine when sweet corn is ready to harvest, first check the silks to see if they have begun to dry and turn brown. Then feel the ear. It should feel firm and full.

Peel back a shuck enough to puncture a few kernels on the ears with your thumbnail. When sweet corn is at its highest quality, the juice from the kernels will be milky white and runny. It’s not ready when the juice is clear and watery. And sweet corn is over-mature and starchy when the juice inside the kernels is thick and dough-like.

Corn usually matures 18-24 days after the tassels appear or 15-20 days after the first silks appear. Watch the corn closely because the quality changes fast. Refrigerate or cook the ears immediately after harvesting.

For more information, the LSU AgCenter has an excellent brochure entitled “Sweet Corn in the Home Garden.” Contact your local LSU AgCenter office or view it online at

Rick Bogren

1/4/2011 1:07:07 AM
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