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Tips on Growing Sweet Corn

By Pinoy Farmer | May 1, 2008

A Short History of Corn

The cultivation of corn (maize) (Zea mays ssp. mays) began over 8,000 years ago in Mesoamerica, a geographical area which includes central and southern Mexico, and Central America. Corn was first domesticated from teosinte (Zea mexicana), an annual grass native to this region. Wild teosinte mostly has value as a fodder plant, as it provides very little edible seeds.

The first archaeological evidence of domesticated corn comes from the San Marcos cave in Tehuacan and the Guilá Naquitz cave in the state of Oaxaca, Mexico. The corn in San Marcos cave is dated to over 5,000 years ago. The cobs from the Guilá Naquitz cave were dated to over 6200 years old.

Researches believe that humans first domesticated corn by selecting the teosinte plants that had the largest amount of edible seeds until they eventually provided a substantial food source. This method probably took several generations to produce the corn we see today. In the process, humans have transformed corn into a plant that can no longer self-sow. Modern corn requires someone to break the hard, tightly bound cob and plant the seeds. Wild teosinte, however, is very fragile and the seeds easily fall off and grow new plants. Interestingly, without human interaction, modern corn would probably cease to exist.

Home gardeners who want to grow corn may choose from several different varieties including popcorn, dent corn, flint corn, pod corn, and sweet corn. Here we’ll focus on growing sweet corn as it is the most popular for the home gardener.

Sweet Corn Varieties

There are three main types of sweet corn available: Sh2, (supersweet), SUSU (normal sugary), and SESE (sugary enhancer). Sweet corn can also be classified by its color: white, yellow, or bi-colored.

Supersweet corn varieties have firm kernels and are very sweet. They are typically not as “creamy” as the other varieties. Note that supersweet corn is more susceptible than the other varieties to cross-pollination and may loose its flavor if grown too close to other non-supersweet corn crops. Normal sugary corns are creamy and sweet and very popular with gardeners. They do not store well after harvesting, and should be eaten within a couple of days. Sugary enhancer varieties have a smooth and buttery texture. For flavor, texture, and ease of growing, this is the best variety.

Sweet Corn Gardening Tips

Where and When to Plant
Plant your corn in full sun and well after any risk of frost. Your corn should receive at least eight hours of sunlight a day. Soil temperatures should be about 60 degrees F for proper germination, and slightly higher for the supersweet varieties. Generally, May and June are good months to plant. You can check your soil temperature with an electronic soil tester if you have any doubts. If you want an early start on your corn, you can consider covering your soil with a plastic mulch, such as clear or black polyethylene, to help warm the soil and promote germination.

When you’re looking for a place to plant your corn, you should keep in mind that it’s important to separate different corn varieties as they may cross pollinate. Additionally, keep an eye out for other people in your area who are growing corn. Corn is pollinated by the wind and can easily be contaminated by other corn crops. About 300 meters distance between different corn crops is recommended.

Soil and Spacing Tips
Plant your seeds in well-draining soils. The kernels may rot if the soil doesn’t dry well and they stay too wet. Test your soil pH with a soil pH tester. It should be around 6.0 to 6.5. You can add limestone to raise the pH if it is low. Add the powdered limestone during fall so that your soil will be ready by next growing season.

Of course, it is always a good idea to add organic compost to your soil. This will balance out drainage and other factors like pH. If you don’t know how, you can check out the Composting Guide site. Also, consider purchasing a high quality composting bin for your home to improve the quality of your compost.

Plant your seeds approximately one inch deep and space them about a foot apart in each row. If you have sandy soil, you can plant your seeds a little deeper. Planting your corn in groups of four rows works well to stimulate pollination. 32 inches between rows is a good standard distance.

Watering and Maintenance Tips
Sweet corn requires frequent watering to produce full, healthy ears. Once the tassels appear, you should be watering at least one inch of water per week. Make sure the soil doesn’t dry out between waterings. If your area is experiencing particularly hot and dry weather, make sure to compensate and water more frequently. Corn will not do well when exposed to prolonged drought.

You should cultivate around the corn to remove weeds. Weeds can become a nightmare for home gardeners growing corn, so weed frequently. If you’re growing a fairly large crop, you should consider a handheld electric cultivator which will greatly reduce the work involved in cultivating. Weeds and debris also attract pests so remove litter when you can. It’s not recommended to cut out the suckers around your corn as these suckers have nothing to do with yields or quality.

Soil solarization is another technique that can also help to reduce problems with weeds. See this site from Seminole County in Florida for more information. Additionally, burning off weeds with propane torches is another way to deal with weeds without harmful chemical herbicides.

Common Problems

Root Rot: If you have cool, moist soil, watch out for this problem. Improve soil drainage with compost and wait for soil temperatures to regulate.
Rust/Leaf Blight: Warmer, wetter parts of the country have problems with these diseases. There are many blight resistant varieties available. Ask your local nursery for recommended cultivars.

Wireworms/White Grubs: These pests come from soils recently planted with sod or alfalfa. Look for birds feeding on the grubs. Tilling and planting with a cover crop, such as winter peas, can help with this problem.

Corn rootworm beetles: This pest goes after corn silk on maturing cornstalks. They can cause problems with pollination. The immature beetles can be found in old corn fields, and when mature, they migrate to feed on tender, new corn. Keep on the lookout as your corn first starts to produce silk.

Corn Smut: This is a fungus that causes the kernels to swell and turn grey and black. In Mexico, it is called Huitlacoche and is consumed as a delicacy. Ask your local extension agent or nursery for smut resistant varieties. Corn smut is more common on white varieties. You can remove the smut by hand and you should destroy it so that it won’t infect other corn plants. If you’re curious, you can actually harvest the smut before it turns black and dries out. Check out this article from the University of Illinois at Urbana-Champaign on the economic importance of Huitlacoche in Mexico: sweetcorn.uiuc.edu/Common-smut/Huitlacoche-WSMBMP.doc. Also see Aztec Gardens for more information on this unusual food.

European corn borers: These pests bore into the stalks and can weaken them to the point of breakage. The larva is cream colored and they are about 1” long. They may eventually work their way into the corn cob. Their eggs begin to hatch in June.

Fall armyworms: This moth lays small pinkish eggs on corn leaves. Adult worms are less than two inches long. They have a Y shaped marking on the head. Late sweet corn is especially susceptible. You can plant early to avoid this pest, as armyworms are at their worst in the late fall.

Flea beetles: These pests attack in the early spring and can carry Stewart’s bacterial wilt disease. This disease will eventually stunt the growth of young corn. Ask your nursery for disease resistant varieties.

Corn earworms: These are brownish, flying moths that will lay eggs in corn silk. They are active mostly at night. The worms will feed on the tips of the ears. You’ll usually not find more than one caterpillar per ear as they are known to devour each other when there is competition. You can avoid this pest with a bit of mineral oil in the tip of the silk tube, or by sealing off the husk with a rubber band. Pheromone traps placed around the cornfield are also an effective control.

Birds: Birds such as crows are common pests for corn farmers. You can use reflective bird tape throughout the rows to scare them off and confuse them. A good old fashion scare crow is also effective.

Harvesting and Storage Tips

The best time to harvest is known as the “milk stage” when the ears are fully formed but not yet ripe. This stage usually lasts about a week. You can determine when your corn is ready to harvest by looking at the silks, husks, and kernels. The silks should be brown and starting to dry, which occurs about 3 weeks after the silks first appear. They husks should hold tightly to the ear and the kernels should produce a little milky fluid when pierced. Supersweets will produce a clearer liquid. Each stalk of corn should yield at least one ear, and sometimes more.
You should harvest your corn in the cooler hours of the morning. Remove the ears of corn by twisting them at the base and pulling them off. After harvest, you can remove the cornstalks and use them as compost.

Store your corn in cool temperatures, usually around 38 degrees F, the cooler the better. If you wait too long to store your corn, you risk changing the flavor and reducing quality, as sugars begin to convert to starch almost right away in the kernels. You can cool your corn by resting it in crushed ice or placing in a container with ice water. After cooling, place your corn in plastic bags with a few small holes punched in them, and then in the refrigerator for storage. Depending on the variety, it is best to eat your corn within a few days after harvest.

sources : http://www.sweetcorngrowingtips.com

Topics: Crops & Vegetables |