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How to Grow Corn

How to Grow Corn

Growing cornCorn is a warm-season annual that is best planted after the soil temperature reaches 60°F (16°C), usually two or three weeks after the last frost in spring. Corn planted in cold, wet soil is unlikely to germinate.
• Corn grows best in air temperatures from 60° to 95°F (16-35°C).

• Corn can take from 60 to 100 days to reach harvest depending upon variety and the amount of heat during the growing season.

About Corn. Corn is a tender annual and a member of the grass family that can grow from 4 to 12 feet (1.2-3.6m) tall. One to two ears of corn form on the side of each tall, green, grass-like stalk. Flowering tassels form at the top of each stalk; pollen falls from the tassels onto silky threads growing from each ear below. Each silk is connected to an unfertilized kernel. Each ear of corn forms as many kernels as the number of silks that were pollinated. (Tassels are the male flowers of the corn plant. Kernels and ears are the female flowers.) Kernels of sweet corn can be yellow, white, black, red, or a combination of colors. A large corn variety may form one or two harvestable ears on each stalk. A dwarf variety may form two or three harvestable ears per stalk. When pollination does not occur the stalk will produce only a cob.

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Corn Yield. Plant 12 to 20 corn plants per household member.

Site. Plant corn in full sun. Corn grows best in loose, well-worked, well-drained soil with a pH of 5.8 to 6.8. Add aged compost to the planting area before planting. Add aged compost to the planting area the autumn before planting.

Corn planted in garden
How to Grow Corn: Corn is a tender, warm-season annual that is best planted after the soil temperature reaches 60°F (16°C), usually 2 or 3 weeks after the last frost in spring.

Corn Planting Time. Corn is a tender, warm-season annual that is best planted after the soil temperature reaches 60°F (16°C), usually 2 or 3 weeks after the last frost in spring. Corn requires 60 to 100 frost-free days to reach harvest depending upon variety and the amount of heat during the growing season. Corn grows best in air temperatures from 60° to 95°F ((16-35°C). Corn planted in cold, wet soil is unlikely to germinate. Corn seed germinates in 10 to 14 days at 75°F (24°C), but the rate of germination may reach only 75 percent. Start corn indoors 2 to 3 weeks before the last frost in spring for transplanting 2 to 3 weeks after the last frost. If your season is long enough, plant successive crops every two to three weeks.

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Corn planted in rowsPlanting and Spacing Corn. Sow corn 1 to 1½ inches (2.5cm) deep. Plant seeds 2 to 4 inches (5-10cm)  apart in short, side-by-side rows to form a block, rather than one long row. You can also grow several plants on mounds or inverted hills. Planting in a block or clump will help ensure pollination. Thin plants from 12 to 18 inches (30-45cm) apart for short varieties and 18 to 24 inches (45-61cm) apart for tall varieties once plants are 4 to 6 inches (10-15cm) tall. Corn planted too closely will require more water and fertilizer and may offer a smaller yield. For a continuous harvest, succession plant corn every two weeks or plant early, midseason, and late varieties at the same time.

More tips: Corn Seed Starting Tips.

Water and Feeding Corn. Keep corn evenly moist and regularly watered. Corn grows fast in hot weather and requires an even supply of moisture to avoid wilting. Avoid overhead watering particularly when tassels appear; water hitting the tassels at the time of pollination can reduce the number of kernels on a cob. Add aged compost and aged manure to planting areas the autumn before planting. Corn is a heavy nitrogen user. Side dress corn with aged compost or compost tea when stalks are 10 inches tall and again when they are 18 inches tall and a third time when they tassel.

More tips: How to Increase Your Corn Crop.

Companion plants. Potatoes, peas, beans, cucumbers, pumpkins, squash. Do not plant corn with berries or pole beans.

Corn Care. Weed corn early to avoid competition for water and nutrients. Corn is shallow rooted so avoid deep cultivation. Crowding stimulates lots of silage, but no cobs. To protect corn from birds cover ears with paper bags after pollination. Poor kernel development can be the result of poor pollination, too few plants resulting in poor pollination, overcrowding, or a potassium deficiency in the soil. If stalks are purple looking there is likely a phosphorus deficiency.

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Container Growing Corn. Corn can be grown in a large container but is not a practical choice for container growing because pollination requires several plants. Plant 5 or 6 seeds in a large five-gallon container.

Corn Pests. Corn can be is attacked by cutworms, wireworms, flea beetles, corn earworms, and corn borers. Look for pests and handpick and destroy them. Corn earworms deposit eggs on developing silks; later the small caterpillars will follow the silks down into the ears, where they feed on the tips. Place a drop of mineral oil inside the tip of each ear to coat and suffocate earworms. Corn borers will tunnel into stalks and ears to begin feeding. Handpicking is the best control. Keep the garden free of debris where earworms and borers can live. Raccoons and many rodents will also attack corn. Use traps or fences to exclude these pests.

Corn Diseases. Corn is susceptible to smut, a fungus disease, and Stewart’s wilt, a bacterial disease. Corn smut will turn kernels gray or black and cause kernels to swell. Destroy affected plants, and do not replant in the same place for two years. Smut spores can survive in the soil for two years.

Stewart’s wilt is a bacterial disease spread by flea beetles. Stewart’s wilt will cause leaves to yellow and plants to become stunted. Plant disease-resistant varieties and control flea beetles by placing wood ash or agricultural lime around plants.

More help with corn problems: Corn Growing Problems: Troubleshooting.

Corn near harvest
Corn is ready for harvest when ears turn dark green, silks turn brown,

Corn Harvest. Corn requires from 60 to 100 days to reach harvest depending on the variety and warm weather. Corn is ready for harvest when ears turn dark green, silks turn brown, and kernels are soft and plump; squeeze a kernel and the juice will be milky, not clear. Pick corn by grabbing the ear and giving it a sharp downward twist. Each stalk of corn will produce one or perhaps two harvestable ears of corn. Harvest usually comes about 20 days after the silks appear. Harvest corn in the morning and plunge ears immediately into cold water to preserve sweetness.

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Storing and Preserving Corn. Corn is best eaten fresh. Corn will keep in the refrigerator for 2 to 4 days; wrap the unopened husk in damp paper towels. Blanched corn on the cob can be frozen for 3 to 6 months.

More tips: How to Harvest and Store Corn.

Sweet Corn Varieties:

  • Early season, yellow corn: ‘Bodacious’ (75 days); ‘Earlivee’ (69 days); ‘Early Sunglow’ (63 days); ‘IlliniChief’ (75 days); ‘Sugar Buns’ (72 days); ‘Tuxedo’ (74 days).
  • Midseason, yellow corn: ‘Golden Bantam’ (83 days); ‘Golden Cross Bantam’ (90 days).
  • Late season, yellow corn: ‘Kandy Korn’ (89 days)
  • Early season, white corn: ‘Platinum Lady’ (85 days); ‘Sugar Snow’ (68 days)
  • Midseason, white corn: ‘Alpine’ (79 days); ‘Argent’ (82 days); ‘Divinity’ (75 days); ‘Pristine’ (79 days)
  • Late season, white corn: ‘How Sweet It Is’ (87 days); ‘Silver Queen’ (94 days); ‘Stowell’s Evergreen’ (100 days)
  • Early season, bi-colored corn: ‘Athos’ (67 days); ‘Double Gem’ (75 days); ‘Quickie’ (65 days); ‘Skyline’ (73 days); ‘Sugar and Gold’ (67 days)
  • Midseason, bi-colored corn: ‘Butter and Sugar’ (73 days); ‘Clockwork’ (78 days); ‘Honey and Cream’ (78 days);
  • Late season, bi-colored corn: ‘Pilot’ (90 days).
  • Space-saving varieties: ‘Baby Corn’ (65 days); ‘Golden Midget’ (65 days).

More tips: Corn Varieties: Best Bets and Easy-to-Grow.

Common name. Corn, sweet corn

Botanical name. Zea mays

Origin. Central America

More tips: Sweet Corn Growing Tips

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53 Comments

    • Check out the Topics Index on the Harvest to Table homepage. There you will find a list of vegetables. Choose articles to help you through each stage of your growing season. In general, I often advise vegetable gardeners to (1) grow what you like to eat; (2) don’t grow more than you can eat or preserve or give away; (3) keep a garden journal of planting dates and expected harvest dates; (4) visit the garden often–then you will see what needs your attention–watering, weeding, and pest and disease control.

    • Please tell me how corn is growing in my yard when no one in my neighborhood has corn but me. I did not plant this corn, I dont even know how to grow anything. Help

      • Plants that grow without the intention of the gardener are often called “volunteers”. Corn seed was dropped in your yard and the corn volunteered because it found a good home. A bird or an animal or a human dropped the seed. If your corn produces ears, take one to a nearby farmers’ market and ask if one of the growers can identify the variety for you.

  1. Why is pole beans a bad companion plant? I have read that beans, corn, and squash form the “three sisters” – the companion plants used traditionally by American Indian tribes. I am very interested in any feedback since I was about to try the three sisters method in my garden.

    • Pole beans are both a good and poor companion for corn. Pole beans and bush beans are good companions for corn because the plants pull nitrogen from the air and turn it into usable nitrogen in the soil. (Corn–like other members of the grass family–thrives on nitrogen.) Pole beans, unlike bush beans, are vigorous climbers and so can take over a corn plant–making life (sunlight and air circulation and pollination if the bean vine grows high enough) problematic; in that sense, pole beans are a poor companion. In the Three Sisters Planting (corn-beans-squash), corn acts as a support or pole for the beans; the squash plant’s large leaves act to shade the soil from summer heat (a sort of living mulch); and the beans provide nitrogen for all three plants.

      • I am curious on spacing when you do this, I am about a month out from planting and since we are planting around 1000 of each we planned to plant them near each other but I am not finding good data on spacing between the three plants and if you plant them this way is it still okay to irrigate instead of traditional watering?

        • We plant sweet corn is ½ inch deep in single rows on 40-inch wide beds. We space plants 6 to 8 inches apart. Overcrowding sweet corn plants can result in non-heading. Spacing them too far apart can result in poor pollination and wind damage.

    • There are two groups of corn–temperate and tropical. Try growing a tropical variety such as Hawaiian Supersweet #10, Sweet Sarah, or Kalaka Supersweet. Temperate varieties that may grow in Costa Rica or other tropic locations are Golden Cross Bantam, Jubilee, and Sure Gold. Look online for corn seed growers for these varieties.

  2. We planted corn the last weekend of May ! The stalks look healthy & tall but there is no sign of any ears/cobs developing yet. We are new at this & wondering if this is normal?

    • Check your seed packet for the number of days to maturity. Corn can take as long as 100 to 110 days to reach maturity depending upon the variety you planted. If your plants are healthy and thriving, be patient.

    • Plant corn during the time of the year when air temperatures will stay between 65F and 86F for 110 days. Temperatures lower will slow growth; temperatures higher can inhibit pollination.

  3. Hi Steve-Curios about the comment in this article about not planting pole beans with corn. We were planning to do a three sisters garden with corn, pole beans and pumpkins. Will the beans truly have an adverse problem with the corn?

    • Three Sisters planting — corn, pole beans, and squash — is an old favorite planting combination; some say it originated with Native American people before Europeans settled North America. Three Sisters is a form of companion plants. Companions help one another in one way or the other. In this case, corn provides vertical support for the pole beans and the corn and beans offer shade for the squash. See more on companion planting in the Index and you may be interested in the article here called Companion Planting in the Vegetable Garden.

    • The reason corn silks turn purple and ears are small towards the end of summer is because there has been little or no kernel development in the ear; in other words, the ear is barren. The likely cause for little or no kernel development is poor pollination earlier in the season. Other causes of purple silks are stresses including cool night temperatures, root restrictions, and water stress (both waterlogged and droughty conditions). These stresses could have occurred earlier in the season and are manifesting themselves now though the purpling of silks can occur early in the season as well as late.

      • Hi Steve, Thank you for your informative website! It is also my first time planting corn. I noticed that my corn silks became pinkish-purple from when they were just two inches long. The silks are still lengthening, yellow-green from where they emerge from the very, very small cobs. Do cobs grow in size simultaneously, as silks lengthen? Is there still hope for cob and kernel development in my situation? I have been saving pollen in a paper bag on nights before rain so that I may manually pollinate my few stalks daily. Thank you for advice!

        • Pinkish-purple corn silks could a sign of lack of phosphorus in the soil. Get a 5-10-10 fertilizer to boost phosphorus in the soil. Cobs will fill out if pollination was complete; each silk must receive pollen which then travels to the seeds for germination. If pollination is hit or miss, the ears will not fill out fully.

  4. Hi. Could you help. It’s our first year on the allotment and so eager we bought our sweetcorn as plants very early when it was cold and kept them in the greenhouse. They looked healthy and we transplanted into bigger pots as the roots were constricted, gradually hardened them off and planted out as soon as the weather warmed up in May. We put well rotted manure in the planting hole and kept it watered. They grew only about a foot tall and although produced a corn on each plant, just stopped. One produced yellow corn but several others stayed white and the husks seemed to rot. Got fed up and dug them out. Will try again but what did we do wrong? Should we have left them in? I have a picture but not sure how to send it. Any advice would be great.

    • Corn husks that rot are likely victim of Fusarium ear rot (a fungal disease). Corn can be left susceptible to this disease when thrips are feeding on the ears. Thrips are barely visible to the eye–about 1/25 of an inch long when fully grown. Thrips suck juices from plant leaves. As they move from plant to plant they can spread disease. Neem oil spray will kill thrips and suppress fungal diseases. Next season, wait until the weather has warmed about two weeks after the last frost to sow corn seed in the garden. (There is no need to start corn indoors unless your growing season is very short). If you do live in a short summer region, choose a short-season variety that will mature easily in your growing season (the time from last spring frost to the first fall frost). Corn is a member of the grass family, so like other grasses, it needs plenty of water for quick, uninterrupted growth. (It sounds like you gave your crop the right nutrients; so you need to be a bit of detective to determine what else could have gone wrong.)

    • From planting to harvest corn requires 55 to 95 days (depending on the variety you plant). The days must be warm and frost-free; the warmer the days, the faster the corn will mature. Plant corn when the soil temperature reaches 60F and you have 3 months of warm days ahead.

  5. My 4yr old son wants to grow corn. We are only looking to grow a small handful of stalks. While this site is very informative I need help with step 1. Can I just buy corn on the cob from my local farmers market and plant a handful of kernels from it? Is there something more or different I need to do procure kernels that will grow based on a lot of the info provided on this post?

    • The key to using corn kernels from corn on the cob that you purchase at the farmers market is whether or not the corn you are purchasing is open-pollinated or hybrid. Ask the farmer what variety he is selling and ask if it is a hybrid or open-pollinated. You want open-pollinated seed; it will grow true–meaning it will grow to be just like the corn on the cob you purchase. Hybrid seed may not grow true; it can revert back to a parent and may not have the characteristics you want. Also, you must allow the seed to dry before you plant it, otherwise the moist seed may rot in the soil.

  6. Thank you so much for your tip that corn needs to be planted around an inch deep and germinates in around 12 days. My brother inherited about 100 acres of flat land in the middle of nowhere from my late uncle. My brother lives a very busy life; however, he would love to see the land used for some kind of harvesting. I wonder if he should look into services that can help take care of the fields for him!

  7. I’m trying something this time that I haven’t tried before. I planted my corn in the garden 4 different dates so I would have fresh corn coming on all thru the summer. so far the early corn made good and already harvested the 2nd planting is now coming on, the third planting will be about 4 weeks before it comes on and the 4th planting is about 5 inches tall now. Will the 4th planting have time to make for the table???

    • If you have 60 to 70 more warm days in your growing season, the fourth crop will mature. The number of crops you can grow is only limited by the length of the growing season which varies from one part of the country to the next.

  8. We harvested our corn to early and the cob looked like a building built by the architect Gaudi! Some kernels were formed somewhere not. But these were also grown in containers. My first try at container growing corn . we haven’t opened the rest of the cob‘s that are in the fridge. We had an extreme heat wave and all of our tassels were already purple but turned brown so I believe I may have pulled my ears too early. I will find out when we open the others. The miniature corn was perfectly formed, very sweet and very tender. Plus I was wondering if blue corn has a purpleish color stock or am I looking at a deficiency? The corn variety is drought resistant corn from the Southwest and I live in California. I don’t know if that has any bearing on the growth either.

    • The corn with missing kernels was not designed by Gaudi; it was insufficiently pollinated. Corn is commonly pollinated by the wind. There are two flowers–male (tassels) and female (silks). Tassels emerge from the top of the corn plant, then open to disperse pollen on the silks which emerge lower, from the immature corn ear. If pollen fails to fall on a silk, it will not be pollinated and no kernel will follow. Ensure the corn receives a breeze when flowers appear; you can also give each plant a gentle shake. A blue corn variety may have a tinge of purple or blue but that can also be a sign of insufficient nitrogen or phosphorus; you might want to test the soil.

  9. Hi, I planted 6 corn stalks in a crate. It’s as tall as me already. 2 months old. And no corn in sight. Temperature was as high as 105′ but I put protection over it. What could be the problem?

    • Perhaps too much nitrogen fertilizer; feed the plants with a dilute solution of fish emulsion; you can also water them with a solution of 1 tablespoon Epsom salt mixed in a gallon of water–this will help flowering.

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