How to Grow and Care for Sweet Corn Plants
Sweet Corn Plant Profile
- 1 Sweet Corn Plant Profile
- 2 A Traditional Summer Treat
- 3 How to Grow Sweet Corn Plants
- 4 Light
- 5 Water
- 6 Temperature and Humidity
- 7 Fertilizer
- 8 Propagating Sweet Corn Plants
- 9 Varieties of Sweet Corn
- 10 Common Pests and Diseases
- 11 Harvesting
- 12 Growing Corn in Small Spaces
- 13 Insect Pests of Stored Grain: Angoumois Grain Moth
- 14 Cornmeal As Weed Killer And Pest Control: How To Use Cornmeal Gluten In The Garden
- 15 Gluten Cornmeal as Weed Killer
- 16 How to Use Cornmeal Gluten in the Garden
- 17 Using Cornmeal Gluten to Kill Ants
A Traditional Summer Treat
Peter Dazeley/Getty Images
Corn is one of the most popular vegetables to grow and eat—all the more delicious when freshly harvested—and it’s surprisingly easy to grow your own. Corn grows from straight, tall 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.
|Botanical Name||Zea mays|
|Common Name||Sweet corn|
|Mature Size||6 to 8 feet tall|
|Sun Exposure||Full sun|
|Soil pH||Neutral to slightly acidic|
|Harvest Time||Late summer. early fall|
|Plant Color||Yellow, white, bicolor, or red|
How to Grow Sweet Corn Plants
Direct-seed your sweet corn in loamy soil and full light. Be sure the plants are deeply watered weekly, and provide plenty of fertilizer. It can take between 60 and 90 days for corn plants to be ready to harvest.
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 six and eight 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 to harvest because of the competition from crows, raccoons, squirrels, and assorted other pests who find corn as delicious as you do. Traditional wisdom says harvest your corn the day before the raccoons do.
To grow well and have the ears fill out, your corn will need a spot that gets full sun.
The soil should be loose and loamy, with a neutral pH (6.0 to 7.0). Heavy soils inhibit corn’s long taproots. The shallow roots you will see on the soil surface are predominantly there to anchor the tall plants.
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 F. 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.
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.
Propagating Sweet Corn Plants
Sweet corn does not transplant well from seedlings unless you are using a biodegradable pot. The best way to propagate sweet corn is direct-seeded 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.
Varieties of Sweet Corn
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; very disease resistant
- Golden Bantam: An open-pollinated heirloom variety, often called the original sweet corn
- Tuxedo: A «supersweet» variety with extra-long ears
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 that 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.
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 you remove the kernels from the husks before freezing or not.
Growing Corn in Small Spaces
There’s nothing better than eating fresh sweet corn harvested from your own garden, boiled up within minutes of picking. The combination of the sweetness and corn flavor makes this vegetable the quintessential summer treat. But sweet corn has a reputation of being a space hog. When we think of growing sweet corn, most of us think of vast fields of plants. The impression is that sweet corn needs lots of room to grow. But you can grow sweet corn in a small backyard garden, a raised bed, or even a container. It’s just a matter of selecting the right varieties, having fertile soil, and making sure the corn gets pollinated properly.
Here’s how to grow sweet corn in a small space in your yard.
Sweet Corn Varieties
There are several types of sweet corn and many varieties to choose from. Heirloom sweet corn varieties have an old-fashioned corn flavor but lose their sweetness quickly after harvest. Newer sugar-enhanced and supersweet varieties have a good combination of sweetness and corn flavor, and they hold their sweetness longer after harvest. However, they can be more finicky about their growing conditions.
The key to growing sweet corn in a small space is to grow blocks of the same variety close together. You can start with shorter varieties that mature early and then experiment with taller, mid- and late-season varieties to extend the harvest season.
Here are some good varieties to try:
‘Ambrosia Hybrid’ — (75 days) This sugar-enhanced (SE) variety produces 8-inch yellow and white ears on 6-1/2-foot-tall plants.
‘Celestial Hybrid’ — (87 days) An 8-1/2-inch, white-eared supersweet corn with good disease resistance. The stalks grow 6-1/2 feet tall. ‘Improved Golden Bantam’ — (80 days) This heirloom variety features sweet, golden kernels on 8-inch ears. The plant only grows 5 to 6 feet tall.
‘Jubilee Hybrid’ — (81 days) These 7-foot stalks produce 8-1/2-inch ears with super sweet yellow kernels.
‘Silver Queen’ — (88 days) This popular, late maturing, heirloom grows 7-1/2 feet tall and produces sweet, white kernels.
‘Sugar Buns Hybrid’ — (72 days) This very early sugar-enhanced sweet corn variety grows 6 feet tall and produces 7-inch yellow ears.
‘Trinity Hybrid’ — (70 days) This bicolor sugar-enhanced variety has 8-inch ears and the stalk only grows 6 feet.
Getting a Jump on the Season
Sweet corn is in the grass family and loves heat and moisture. Don’t be in a rush to plant sweet corn in the garden or in a container. If you’re growing old-fashioned varieties, wait until the soil temperature is at least 55 degress F to plant seeds. For sugar-enhanced and supersweet varieties, wait until the soil is at least 60 degrees F.
You can get a jump on the season, especially if you’re growing in a raised bed or container, by laying black plastic over the soil two weeks before planting to hasten the soil warming, or by presprouting seeds indoors. To presprout, soak seeds in a moist paper towel overnight and then plant in the garden. You can even start corn plants indoors in pots and when the seedlings are a few inches tall, transplant them into your plot. Just make sure you protect these early seedlings from cold nights by laying a floating row cover over plants on chilly evenings.
Small Space Design
When growing corn in a small space, think short thick rows. Each kernel of corn is connected to a corn silk. These fine hairs help transport the corn pollen to the kernel for proper development. The pollen drops down onto the silks from the tassels at the top of the plant. In order to have properly filled out corn ears, pollen needs to fall on all the corn silks. If you plant in short rows close together, it’s more likely proper pollination will occur. Plant 4 to 5 plants in a container or plant in beds of at least 4 rows, no more than 4 feet long, spaced 1 foot apart.
While growing corn in short rows close together helps pollination, to insure success consider hand pollinating the ears. Here’s how. In the morning when the corn tassels have fully extended, slip a brown paper bag over a tassel and shake the pollen loose into the bag. Spread out the silk on each individual corn ear and sprinkle pollen on the silks. Repeat this process three days in a row.
For proper growing, keep your corn well watered, weeded, and fertilized. Spread compost in small beds before planting and side-dress with 3 pounds of 5-10-5 fertilizer per 100 square feet before tasseling. Keep containers well watered and fertilized every few weeks with a balanced fertilizer.
Your biggest pest may be an animal. Keep raccoons out of the patch with an electric fence, or cover each ripening ear with a paper bag sealed with tape.
QUESTION OF THE WEEK
Blight on Cucumbers
Q: I’ve grown cucumbers before with good success. Last year, however, my cukes started out great, then yellowed, wilted, and died. What happened and how can I avoid it this year?
A: It sounds like your cucumbers had a bacterial blight disease. This disease attacks mostly cucumbers and melons, causing the leaves to yellow and the plant to die prematurely. A telltale sign of bacterial wilt disease is the white, sticky juice you find inside the infected cucumber stem when you cut it open. It’s commonly spread by the feeding of cucumber beetles. To control this disease, plant blight-resistant varieties and control the cucumber beetle. Simple cucumber beetle controls include not planting cucumbers in the same area each year, cleaning up crop debris well before planting, and placing a floating row cover over the crop before flowers form. After flowers open, remove the row cover so bees can pollinate the flowers. Spray plants with pyrethrum to keep cucumber beetle adults from spreading the disease.
Insect Pests of Stored Grain: Angoumois Grain Moth
ENTFACT-156: Insect Pests of Stored Grain: Angoumois Grain Moth | Download PDF
Doug Johnson, Extension Entomologist
University of Kentucky College of Agriculture, Food and Environment
The Angoumois grain moth (AGM) can cause significant loss of crib-stored ear corn held for more than one year. This insect is a primary stored grain pest because its immature (caterpillar) stages develop entirely within a grain kernel. While AGM can attack several grains, it is most often associated with ear corn and is rare in shelled corn. An infested kernel is mostly hollow with a round hole through which the moth emerges. It will weigh about 20% less than a sound kernel. AGM-infested grain usually has an unpleasant odor so animals may refuse to eat it or limit their consumption.
The exit holes in AGM-infested kernels are similar to those produced by grain weevils so finding adults is one way to identify the cause. Adult AGM are small (1/2 inch wing spread), tan to grey moths with fringed wings and the forward portion of the hind wings have distinctive fingerlike tips; adults do not feed. Grain weevils are dark brown beetles with prominent snouts. Weevils and AGM can develop in both ear corn and shelled kernels. AGM and saw-toothed grain beetle can coexist, but maize weevil or lesser grain borer will suppress AGM population.
Like most stored grain insects, AGM infestations can begin from adults emerging from small amounts of carry-over corn in a crib. However, infestations can also begin in the field from moths laying eggs before harvest. The shuck provides protection against this insect. Nevertheless, moths can lay their eggs on kernels exposed due to a loose or damaged shuck.
AGM moths lay their eggs in the gaps between kernels. Upon hatching, the tiny caterpillars immediately bore into a grain kernel, covering the hole after they enter. These larvae go through three molts will feeding on the interior of the kernel. Just before pupating, the mature caterpillar chews a circular hole leaving a thin film over the future exit, through which the adult moth emerges.
The length of this life cycle depends on temperature with completion in 30 days at 86o F and 40 days at 77o F. Minimum temperature and relative humidity for development is 61o F/30% Rh while the optimum is 86o F/75%/ Rh and the maximum is 95o F. Generally, AGM will have four to five generations per year with the larvae being dormant in the coldest winter months; but may have as many as 10-12 generations in heated warehouses.
Prevention: The techniques listed below should reduce the chance of an infestation and if insecticides have to be employed they will have a better result.
- AGM is the only stored product insect known to infest standing grain in the field. Data suggest that infestation is reduced if grain moisture is greater than 30%. However, storage at this high level of moisture can result in many other problems, like fungal growth. Below that level the pest prefers damp grain in preference to very dry grain.
- Carry-over grain can be a major source of AGM and other stored grain insect pests. It should be removed and discarded (sold, fed, buried, or spread on open ground in winter) to prevent the emerging adult moths from flying back to re-infest the newly stored grain. If leftover grain must be retained, it should be properly fumigated. This is, without question, the technique of last resort. Proper fumigation is costly, dangerous, and requires considerable equipment, supplies, and knowledge along with substantial paper work and notification.
- Removal of all spilled grain from in and around the storage area is an important method of reducing the infesting population.
- All equipment used to harvest, move, and store the grain should be thoroughly cleaned well before these events occur.
- If possible shell the corn from the cob and store in a covered solid sided facility through which air may pass. This will limit AGM infestation to the uncovered grain surface.
- Storage of ear or shelled corn in a solid sided facility through which air may be moved will allow for drying of the grain, thus reducing the chance of mold and limiting the ability of AGM to infest the kernels.
Detection: AGM moths may be monitored by capture in “Delta™” sticky traps baited with a lure containing their sexual attractant. Hang these traps in a space over the stored grain. Count and record the number of moths captured per unit each time. There is no absolute number for use as a threshold. Nevertheless, after a period of use one can estimate how many moths need to be caught to indicate an important population.
Protection in the Crib: Wire, or slatted cribs, or ears piled under open-sided covers may provide some protection from weather but will not protect against insect infestation. There is little one can do aside from the prevention items listed above to control AGM in these structures. One might try to apply a liquid insecticide to the ears, but coverage will be very inefficient. Some AGM moths will be killed but it is unlikely that coverage will be thorough enough to prevent infestation.
Protection in the Bin (solid wall steel or concrete): Infestation of shelled corn stored in sound standard steel or concrete bins is much less likely than on the ear in a crib. However, it may occur, especially in the second and subsequent years of storage. Generally, this begins on the top surface of the grain mass and is somewhat self-limiting. The delicate moths cannot penetrate deeper than the top few inches of shelled grain. However, if storage managers are not vigilant, an accumulation of destroyed kernels, dead insects and excrement can result in a “crust” over the grain. This will reduce air flow and can result in spoiled grain below the surface. Applying a “cap-out” treatment of an approved insecticide product worked into the top 4” inches of the grain and deploying “pest strips” AKA “shield strips” hung in a void over the grain are helpful in controlling this pest.
Remediation: Control of existing infestations in either a crib or bin is possible through fumigation. However, the two situations have different obstacles. Typical on-farm metal grain bins will be less complicated to seal. Wire or slatted cribs would have to be completely enclosed in an impermeable material like 4-mil plastic. The object in both cases is to prevent any of the fumigant gas from escaping. Fumigation kills by holding a specific concentration of poison gas in a given volume of space for a specific amount of time at a specific temperature. Think of inflating a balloon. If the air escapes, the balloon deflates. When fumigating, if the gas escapes, insect control will not occur or occur at a reduced level. Spraying infested ears with a liquid insecticide is unlikely to provide desirable results.
Insecticides: Insecticides for use against AGM and other stored grain insects may be found in the appropriate ENT- publication listed in the References below.
- Back, E. 1920. Angoumois Grain Moth. Farmers Bulletin 1156. USDA.
- Jacobs, Sr., S. and D. Calvin. 1990. Angoumois Grain Moth. SG-1. PSU-CES. http://ento.psu.edu/extension/factsheets/pdf/anggrainmoth.pdf
- Johnson, D. n.d. Insect Pests of Stored Grain: Indian meal Moth. Entfact-136. http://www2.ca.uky.edu/entomology/entfacts/entfactpdf/ef136.pdf
- Johnson, D. ENT-16. Insecticide Recommendations for Field Corn. http://pest.ca.uky.edu/EXT/Recs/ENT16-Field%20corn.pdf
- Johnson, D. ENT-24. Insecticide Recommendations for Grain Sorghum (Milo) http://pest.ca.uky.edu/EXT/Recs/ENT24-Sorghum.pdf
- Johnson, D. ENT-47. Insecticide Recommendations for Small Grains. http://pest.ca.uky.edu/EXT/Recs/ENT47-SmallGrain.pdf
- Johnson, D. ENT-62. Insecticide Recommendations for Popcorn. http://pest.ca.uky.edu/EXT/Recs/ENT62-Popcorn.pdf
- Mason, L. 2010. Angoumois Grain Moth. Purdue Extension, E-236-W http://extension.entm.purdue.edu/publications/E-236.pdf
- Weston, P., R. Barney and J. Sedlacek. 1993. Planting Date Influences Preharvest Infestation of Dent Corn by Angoumois Grain Moth (Lepidoptera: Gelechiidae). J. Econ. Entomol. 86(1):174-180.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!
Cornmeal As Weed Killer And Pest Control: How To Use Cornmeal Gluten In The Garden
Cornmeal gluten, commonly referred to as corn gluten meal (CGM), is the by-product of corn wet milling. It is used to feed cattle, fish, dogs, and poultry. Gluten meal is known as a natural substitute for chemical pre-emergent herbicides. Using this cornmeal as weed killer is a great way to eradicate weeds without the threat of toxic chemicals. If you have pets or small children, gluten meal is a great option.
Gluten Cornmeal as Weed Killer
Researchers at Iowa State University discovered by accident that cornmeal gluten acts as an herbicide while they were doing disease research. They saw that corn gluten meal kept grass and other seeds, such as crabgrass, dandelions and chickweed, from sprouting.
It is important to note that cornmeal gluten is only effective against seeds, not plants that are mature, and is most effective with corn gluten having at least 60% proteins in it. For annual weeds that are growing, plain cornmeal products will not kill it. These weeds include:
Perennial weeds will not be damaged either. They pop back up year after year because their roots survive under the soil over winter. Some of these include:
However, cornmeal gluten will stop the seeds that these weeds shed in the summer so that the weeds will not increase. With consistent use of gluten meal products, these weeds will gradually decline.
How to Use Cornmeal Gluten in the Garden
Many people use corn gluten on their lawns, but it can be safely and effectively used in gardens as well. Using gluten cornmeal in gardens is a great way to keep weed seeds from sprouting and will not damage existing plants, shrubs or trees.
Be sure to follow the application instructions on the package and apply before weeds start to grow. Sometimes this can be a very tight window, but is best done in early spring. In flower and vegetable beds where seeds are sown, be sure to wait to apply at least until the seeds are grown up a bit. If applied too early, it can prevent these seeds from sprouting.
Using Cornmeal Gluten to Kill Ants
Cornmeal gluten is also a popular method to control ants. Pouring it wherever you see ants traveling is the best option. They will pick up the gluten and take it to the nest where they will feed on it. Because the ants cannot digest this cornmeal product, they will starve to death. It may take up to a week or so before you see your ant population dwindling.
Tip: If you have large areas to cover, you can try a spray form for ease of application. Apply every four weeks, or after heavy rains, during the growing season to maintain effectiveness.