Know Before You Grow: Corn

Corn is one of the most versatile and best-loved veggies you can grow. It's been cultivated for thousands of years, increasing in popularity over time, as its attributes have become more and more obvious. Not only is it delicious in a wide variety of dishes as well as fresh from the stalk, but its uses go well beyond the culinary world. From corn-on-the-cob and popcorn to syrups and cereals and an abundance of other products (edible and not), this tasty vegetable is truly remarkable.

Choosing a Corn Variety

When choosing what type of corn to grow, you'll be able to pick from white, yellow, and bicolor varieties as well as consider a number of other traits that affect taste and tenderness. Here's a list of different hybrid varieties and their main characteristics:

Regular Sweet Hybrids—Traditional, old-fashioned corn flavor, delicious without an emphasis on sweetness. High yielding.
Sugar Enhanced Varieties—Sweeter than regular strains, and with a sweetness that lasts longer after the corn has been picked. A creamy, tender texture and no planting isolation needed from other sweet corn.
Super Sweet Varieties—Bred for twice the sweetness of regular corn. Will hold their tenderness and sweetness up to two weeks. They must be planted in totally warm soil and kept isolated from other types by 200 feet or 14 days planting time.
New Triple Sweet Varieties—Wonderfully sweet, but they were bred to add more original corn taste to the sweetness, improve crunchy texture, and hold their flavor and sweetness even longer. Requires no isolation from other sweet corns.

When to Start Corn Seeds

Corn is best sown outdoors in situ after all danger of frost has past in spring. Sow in warm soil—optimum temperature is at least 6°F. Sweet corn can be started indoors 2 weeks before the last frost at a temperature of 70 to 75°F, but direct sowing is recommended.

How to Start Corn Seeds

If you want a continuous crop, sow every two weeks until early spring. Sow at a depth of 4 times the size of the seed in rows that are 24 to 36 inches apart. Plant in full sun in a rich, moist, well-drained soil. Once the seedlings appear, thin them to 3 to 12 inches apart. If you have started them inside and are transplanting them, do so when they have at least two sets of true leaves and allow them the same amount of space as previously mentioned. Expect germination in 7 to 10 days.

Special Considerations

Cross-pollination can occur between different varieties of corn, affecting taste, color, and other qualities. To prevent this, isolate each type by at least 700 feet, or allow at least 14 days between times of maturity.

Do not plant sooner than 10 days to 2 weeks after the date of the last killing frost. If you plant too early, your seedlings may die or their growth can be delayed.

Since corn is wind pollinated, it's better to plant 4 or more short, side-by-side rows than 1 or 2 long rows. This will help pollination and ear development.

Growing Tips for Corn

• Side dress your corn plants with a high-nitrogen fertilizer.
  
• Harvest your sweet corn once the silks have dried—this will be approximately 3 weeks after silking.
  
• Harvesting: break the stem of the ear (shank) close to the ear. Avoid breaking the main stock or tearing the stem from the stalk. Just hold the ear near the base and bend it down sharply. You can also bend it to the side.
  
• You can expect at least one ear (sometimes more) from each stalk.
  
• In order to maintain the sugar content you will want to refrigerate your sweet corn right away.

Pests and Problems to Watch For

• Corn borer—This moth's larvae feeds on all above-ground tissues of the plant. The cavities they produce interfere with the translocation of water and nutrients, thus reducing the strength of both the stalk and the ear shank. Some methods of control include using a pest-resistant variety, destroying infected stalks at the end of the season, and harvesting early before the moths have a chance to lay eggs.
  
• Corn earworm—These caterpillars feed on the tips of the ears of corn, devouring the kernels and sometimes even destroying the silks before pollination has completed. This results in deformed ears that are susceptible to disease and mold. They can be controlled with Bt, a natural bacteria that produces toxic proteins that kill certain insects. You can also till in fall and spring to expose pupae to wind, weather, and predators, release beneficial insects such as trichogramma wasps, lacewings, minute pirate bugs, and damsel bugs, or use botanical insecticides (always read instructions and cautions before use).
  
• Smut—Corn smut is caused by a fungus, and it can be removed by hand and buried or burned. Since the spores can get into your corn through injured parts of the plant, try to avoid injury of roots, stalks, and leaves during cultivation. Also, plant disease-resistant varieties when possible, and at the end of the season, plow diseased stalks to bury any surviving spores.
  
• Stewart's disease (bacterial wilt)—This disease is caused by a bacteria that's transmitted by several insects, namely the flea beetle, which will over winter and spread the disease once it starts feeding on the new year's crop. To control it, plant disease-resistant plants whenever possible, eliminate or discourage the presence of flea beetles, and don't use seeds that were produced in a field contaminated with Stewart's wilt.
  
• Flea beetle—Flea beetles, so named for their tendency to jump when disturbed, love corn. They produce a characteristic injury to leaves known as "shot-holing." Young plants and seedlings are particularly susceptible to this damage. You can use Sevin® Dust or organic Neem oil to control them.

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