All About Growing Sweet Corn

Your all-inclusive guide to growing sweet corn. Read about the sweet corn varieties best suited to home gardens, when and how to plant sweet corn seed, disease and pest prevention, and harvesting and seed saving.
June/July 2008
http://www.motherearthnews.com/organic-gardening/growing-sweet-corn-zmaz08jjzmcc.aspx
Everyone loves sweet corn — why not plant your own?


Illustration by Keith Ward

(For details on growing many other vegetables and fruits, visit our Crop at a Glance collection page or check out our Food Gardening Guide app.)

Isn’t it time to make mouthwatering sweet corn one of your hit crops this summer? Growing sweet corn requires warm soil (above 65 degrees Fahrenheit) so early summer is prime planting time. To stretch your harvest season, grow both early and midseason sweet corn varieties.

Types of Sweet Corn to Try

Open-pollinated sweet corn varieties offer traditional corn flavor, but rapidly convert sugar to starch, so they must be picked at just the right time. They often require less fertilizer than hybrids, and seeds can be saved from year to year.

Kernels of sugary-enhanced hybrid varieties remain sweet for a week or more, and feature tender texture combined with rich corn flavor.

Super-sweet hybrids produce exceptionally sweet, crisp kernels good for freezing. Super-sweet varieties must be planted at least 30 feet from other types of sweet corn to prevent cross pollination, which ruins their flavor.

Synergistic sweet corn varieties have a balance of sugary-enhanced and super-sweet kernels.

For more information on types of sweet corn and our recommended varieties, see our Sweet Corn at a Glance chart.

When to Plant Sweet Corn

In late spring or early summer, sow seeds in warm, fertile and well-worked soil that contains plenty of nitrogen. Sow early sweet corn varieties one to two weeks before main season varieties for a longer harvest season. Many gardeners sow their early sweet corn when apple trees are in full bloom.

How to Plant Sweet Corn

Thoroughly mix in a 1-inch layer of fresh grass clippings, compost or well-rotted manure along with alfalfa meal, soybean meal or another high-nitrogen organic fertilizer (follow label directions). Sow seeds 1 inch deep and 4 inches apart, in blocks of at least three rows spaced about 24 inches apart. Thin early varieties to 8 inches apart; thin taller midseason and late varieties to 12 inches apart.

Harvesting and Storage

Once an ear feels plump and full when you squeeze it, pull back the shuck near the tip and pierce a kernel with your fingernail; it’s ready to harvest if the juice is milky.

Try to harvest sweet corn in the morning, when the ears are cool. Refrigerate them immediately or put the corn in a cooler and layer it with ice. Sweet corn can be canned in a pressure canner, but most people prefer the speed and convenience of freezing. Blanched corn off the cob takes up much less freezer space compared to whole ears.

Saving Seeds

Most sweet corn varieties are complex hybrids, so don’t expect good results from saving and replanting the seeds. To save seeds from open-pollinated varieties, allow perfect ears to dry on the plants until the husks turn tan. Continue to dry them indoors until a few kernels fall away when you twist the ear between your hands. Store seeds in a cool, dry place for up to two years. (To find the varieties you want, use our nifty new seed search.)

Pest and Disease Prevention Tips

  • Grublike gray to brown corn earworms feed on corn silks and kernels. They are larvae of moths that lay eggs in the tips of immature ears. To limit damage, use a squirt bottle to place five to six drops of vegetable oil in the tip of each new ear. For nearly worm-free harvests, add Bacillus thuringiensis (also known as Bt) organic insecticide to the oil. If earworms are minimal, simply break off the blemished tips as you shuck. Varieties with tight husk tips (such as ‘Argent’) often show only modest earworm damage.
  • A fungal disease called “corn smut” causes kernels to become black, swollen and distorted. You can limit its spread by removing infected ears. Revered in Mexico as a delicacy, blobs of corn smut actually are edible, and resemble mushrooms when cooked.
  • Inch-long striped army worms are common pests of late corn varieties, but early maturing varieties rarely are damaged. Tachinid flies and other beneficials kill large numbers of fall army worms, or you can use a spinosad-based pesticide. 
  • Raccoons closely monitor sweet corn’s progress and stage nighttime raids just as it reaches perfection. To protect nearly ripe ears, tape the ears to the stalk with packing tape, or try some of the other deterrents suggested by the Internet Center for Wildlife Damage Management.

Growing Sweet Corn Tips

  • Precede sweet corn with a cover crop of hairy vetch or another legume to boost the soil’s nitrogen supply. In warm weather, sweet corn can be sown one to two weeks after a cover crop is cut down or turned under.
  • Sweet corn seed must germinate rapidly or it will rot. For best germination, soak seeds in clean water overnight before sowing in warm soil (65 degrees).
  • Hybrid sweet corn is bred to grow at close spacing with heavy fertilization. To keep plants supplied with nitrogen, fertilize before planting, then side dress them with a high nitrogen fertilizer such as cottonseed or blood meal when the plants are 1 foot tall, and again when tassels appear.
  • If plants are blown over by gusty summer thunderstorms, give them a few sunny days to right themselves. It won’t hurt nearly mature plants to grow crooked, but you may need to prop up young plants that don’t get back up by themselves. To prevent this problem, called “lodging,” hill up soil over the base of the plants as you hoe out weeds.
  • The best way to fit sweet corn into a small garden is to grow early varieties in hills comprising six to eight plants. Corn is pollinated when wind carries pollen onto emerging strands of silk. To assure big, well-filled ears in a small planting, gather pinches of dusty pollen from corn tassels and sprinkle it onto the silks once or twice a day.

In the Kitchen

Immediately refrigerate sweet corn to preserve its flavor. You can boil, steam or grill full ears, cut off whole kernels or make creamed corn. To get kernels like those found in canned and frozen corn, blanch ears in boiling water for a few minutes, then cut off the kernels. For creamy corn kernels, cut the kernels from raw ears, and use a spoon to scrape the remaining milky juice off the cobs.


Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on .