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Corn Growing Problems: Troubleshooting

Corn growing
To come to harvest quickly corn requires warm temperatures, rich soil, and even, regular watering. Corn is wind-pollinated so planting in blocks or multiple rows to ensure pollination is important.

To come to harvest quickly corn requires warm temperatures, rich soil, and even, regular watering. Corn is wind-pollinated so planting in blocks or multiple rows to ensure pollination is important.

Here is a troubleshooting list of possible corn growing problems with control and cure suggestions: (Read to the bottom of this post for corn growing success tips.)

Corn Problems and Solutions:

• Corn does not emerge. Soil may be cold or damp. Plant later when the soil and temperatures are warmer; make sure soil is well-draining by adding aged compost and organic matter to soil.

• Insides of seed and young plants are eaten. Corn wireworm or the seed corn maggot is eating the seed. The corn wireworm is the larvae of the click beetle; the click beetle is reddish brown or black to ¾ inches long. Wireworms are brown or yellow and leathery to 1½ inches long. The seed corn maggot is a yellowish-white legless maggot, the larvae of a fly. The maggot feeds on the inside of sprouting seed. Cultivate the planting bed in fall to expose larvae to birds. Spade the corn bed and let it lie fallow every third season. To trap: use pieces of potato on a spike setting them 2 to 4 inches into the soil; check the traps twice a week. Pick and destroy wireworms and maggots from the potato.

• Seedlings are cut off near the soil surface. Cutworms are gray or brown grubs that hide in the soil by day and feed at night. Handpick grubs from the soil at the base of plants. Remove weeds and keep the garden free of plant debris. Place a 3-inch cardboard collars around the stems of seedlings and push the collars 1 inch into the soil.

• Seedlings are uprooted. Crows and birds will pull up seedlings to feed on seed. Cover seedlings with bird block or row covers until they are established.

• Stalks fall over. European corn borers are grayish pink caterpillars with dark head (more below); they can tunnel through stalks and weaken them. Use Bacillus thuringiensis and garden cleanup to control borers. Too much nitrogen also can leave stalks lush and green but weak. Test soil. Adjust fertilization. Avoid using fertilizers too rich in nitrogen. Feed plants with aged compost.

• Stalks and leaves deformed, bent over, or may fail to unfurl; plants are stunted. Aphids are small soft-bodied insects–green and gray–that cluster on undersides of leaves. Aphids leave behind a sticky excrement called honeydew; black sooty mold may grow on honeydew. Spray away aphids with a blast of water; use insecticidal soap; aluminum mulch will disorient aphids. Aphid predators include lacewing flies, ladybugs, and praying mantis.

• Tiny shot holes in leaves. The corn flea beetle can riddle leaves with small holes and transmit Stewart’s wilt, a bacterial disease that leaves the plant’s vascular system clogged with slime; infected plants wilt, become stunted and die. Pick off beetles; cultivate the garden to disturb the insect life cycle. Spray with pyrethrum or rotenone.

• Large holes in leaves. Armyworm, corn earworm, various beetles, and grasshoppers eat corn leaves and foliage. Handpick insects and destroy or place them in soapy water. Loss of small amount of leaf tissue will not reduce yields. Plant early corn varieties to avoid armyworms. Use commercial traps with floral lures. Cultivate in the fall to expose larvae.

• Holes in leaves near whorls. European corn borer; larvae are light brown to pinkish caterpillars with dark brown heads and dark spots on the body; adult moth is light brown with a ¾-inch wingspan. Larvae feed on corn whorls then bore into stalks. They also feed on tassels and kernels. Handpick and destroy larvae. Apply Bacillus thuringiensis. Remove and destroy all infested stalks at the end of the season.

• Leaf edges roll inwards. Soil moisture may be inadequate. Corn makes rapid growth after ears form and begins to mature; this requires consistent moisture. Water corn deeply, up to 2 or 3 hours at a time. When soil dries to a depth of 4 inches, water again. Place 2 to 3 inches of organic mulch on planting bed to conserve moisture.

• Leaves are mottled and streaked yellow and green; leaves yellow and die along the margins; growth is slowed or stunted. Mosaic virus and maize dwarf mosaic virus has no cure. It is spread by beetles. Plant mosaic virus-resistant varieties. Destroy infected plants and keep weeds and grasses down that host aphids beetles. Do not handle healthy plants after infected one.

• Yellow striping on leaves. Stewart’s wilt is a bacterial disease that results in the plant’s vascular system becoming clogged with slime; infected plants will yellow, wilt, become stunted, and die. Control flea beetles which spread the disease. Pick off beetles; cultivate the garden to disturb the insect life cycle. Spray with pyrethrum or rotenone.

Plant tolerant varieties.

• Leaves have purple margins starting with leaves at the bottom of the plant; plant may be stunted. Phosphorus deficiency. Perform a soil test; add bonemeal to the top of the planting bed at a rate of 2 to 3 pounds per 100 square feet. Use a commercial fertilizer rich in phosphorus 5-10-5 is good.

• Reddish-brown blisters on the top of leaves and stalks; leaves may turn yellow. Rust is caused by a fungus; rusty-colored spores grow on the plant. Rust favors warm, humid weather. Plant rust-resistant varieties. Avoid overhead irrigation. Prune away infected leaves.

• Grayish or tan oval spots on leaves. Northern corn leaf blight and southern corn leaf blight are fungal diseases that favor wet conditions. Add aged compost or organic material to planting beds to keep soil well-drained. Avoid overhead irrigation. Keep garden clean of debris and weeds which can harbor fungus spores. Plant resistant varieties.

• Leaves yellow as tassels form. Insufficient nitrogen. Side dress plants with aged compost. Water with compost tea or fish emulsion. Add aged compost to planting beds in advance of planting.

• Gray-white gnarled growths or galls on ears and leaves. Corn smut is a fungus disease. Remove and destroy galls as soon as found when they are still white. Do not allow black powdery spores from galls to fall into soil. Plant resistant varieties. Problem is more common in late harvests.

• Ears only partly filled, silks are chewed short or clipped off. Earwigs, Japanese beetles, and corn rootworm beetles feed on silks which prevents pollination or causes poor kernel development. Check ears daily for earwigs and beetles; handpick and destroy. Spray plants with hot pepper and garlic repellant. Place traps around the garden to collect pests. Keep garden free of weeds and debris.

• Incomplete kernel development; ears partially filled with ripe kernels; shriveled kernels. Each individual kernel must be pollinated; kernels that don’t receive pollen will not fill out. Pollen from male tassels must reach the female silks. Several possible causes: (1) Poor pollination can happen when not enough plants are planted; plant at least 3 to 4 rows at least 8 feet long. (2) Hot weather or high winds during pollination. Pollen sheds 2 to 3 weeks before harvest. (3) Insufficient soil moisture; keep corn evenly moist especially from silking to harvest. (4) Inadequate fertilizer or soil fertility; add aged compost to planting beds. Check for potassium deficiency. Plant varieties adapted to your area. (5) Birds are eating kernels; put paper bags over ears after pollination.

• Worms eat down through kernels; ears look brown and eaten. Corn earworm is a brown-headed caterpillar with lengthwise stripes to 2 inches long; the adult is a night-flying moth with brownish or olive wings and bright green eyes. The worm finds its way into the whorl of the corn plant to burrow down and eat developing tassels. Apply 20 drops of mineral oil just inside the ear tip 3 to 7 days after silks first appear. Break off the wormy end of ear and discard. Plant early-maturing varieties to avoid earworms; varieties such as ‘Country Gentleman’, ‘Golden Security’, and ‘Silver Cross Bantam’ have long, tight husks. Use commercial traps. Handpick caterpillars and destroy. Dust with Sevin.

• Stalks produce small ears. Plants are spaced too close together; plant early varieties at least 8 inches apart; space later varieties 12 to 15 inches apart.

• Popped kernels, kernels look like popcorn. Seed coats will sometime break at the weakest point. No cure. Plant another variety.

• Kernels are pink and moldy; brown lesions on stalks near joints; stalks rotten inside. Fungi can cause rots. Keep garden free of plant debris and weeds that can harbor fungus spores. Remove diseased plants. Make sure soil is well-drained; add aged compost to planting beds twice a year. Keep soil evenly moist but not wet.

Corn Growing Success Tips:

Planting. Grow corn in full sun. Corn requires moist, well-drained soil rich in organic matter. Prepare planting beds or planting mounds with plenty of aged compost. Additionally, sprinkle planting beds with nitrogen-rich cottonseed meal or soybean meal, about 3 pounds per 100 square feet. Plant corn in mounds or hills–thin each hill to 3 plants–or in raised beds. Mounds and raised beds warm early in the season and are well drained.

Block planting. Plant corn in blocks or short, multiple rows. Space plants about 15 inches apart with at least 4 rows and at least 4 plants in each row. Block planting will improve pollination; corn drops pollen from its tassels down to the silks in the ears below. Planted in a block, corn pollen that drifts on the breeze is more likely to find its way to an ear and silks below.

Plant time. Sow corn in the garden after the last frost in spring; it is best to plant corn when the soil has warmed to at least 62°F. Succession plant corn every two weeks for a continuous harvest. Corn can be started indoors 3 to 4 weeks before planting out; start seed in biodegradable pots so that roots are not disturbed when transplanted.

Care. Corn requires even, regular watering. Use a soaker hose to keep corn moist, about 2 inches of water each week. Add 1 to 2 inches of mulch between stalks to conserve soil moisture. Side dress corn with aged compost or a balanced fertilizer 1 month after planting and again when the tassels form.

Harvest. Begin picking corn 3 weeks after the first silks appear. When silks brown and begin to dry the corn is ripe. Check the ears to see that they are filled to the tip with kernels. To further test for ripeness, press a kernel with your fingernail, if the juice is milky white the ear is ripe.

More tips: How to Grow Corn.

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131 Comments

  1. Thanks for your informative post. This is my second year growing corn. After reading your post I think I do not have enough plants for adequate pollination so will plant more next year. At least I would if I could find a solution to my other problem, my corn tastes really bad! When you bite into the cooked corn, the outside of the kernels are a little softer, have a little more give than corn I’m used to. The inside is extremely starchy and just inedible. Any ideas. Thanks very much.

  2. Corn that tastes starchy has likely been left on the plant a few days too long; the sugars are converting to starch. Keep a garden calendar; mark the date you plant and count ahead the number of days to maturity–then look to harvest close to that date. Keep an eye on your corn crop, when the first silks appear expect to begin your harvest about 3 weeks later; this is how long it will take the ears to fill out and ripen. When the silk turn dry, brown and ears feel full to the tip, it is time to harvest; peel back the husk and do the “milk” test with your fingernail. A white juice will drip from a ripe ear of corn. The sweetest, best tasting corn is picked and eaten very, very soon after harvest; waiting too long will bring disappointment. For a continuous harvest, stagger your planting over several weeks or plant varieties that come to flower and harvest at different times; but plant corn in blocks of a dozen or more plants to ensure pollination.

  3. i suspect my maize stalks are bent over because of application of fertilizer with nitrogen. It is not stalk borer because i have sprayed for this. Is there a way to improve/straighten the maize stalks? How should i deal with it urgently? Many thanks

    • If you suspect you have over-fertilized your crop, water is likely the best solution; water to leach the fertilizer deeper into the soil past the plant’s roots. If the stalks are falling, you may want to place stakes along rows and then use garden twine or wire to “fence them in” and keep them upright. Too much fertilizer can cause a variety of crop problems–plants will actually grow weaker not stronger. Amending the soil with aged compost and aged manure before planting will satisfy most plant nutrient requirements and allow you to cut down on the use of extra fertilizers.

  4. I have a stand of “Truckers Favorite” sweet corn which came with a bucketful of assorted seeds from a sustainable seed supplier. I planted the corn in a patch of very fertile soil where my barn used to be, and after a cold start, it grew very quickly. Some of the stalks are now over eight feet tall and as large as my wrist, and most of the corn is taller than the old foundation walls. My problem is that it is now the first week of August in Maine, but there are no tassels and no signs of ears apparent on the stalks at all, as far as I can see. I do have another variety which seems to be growing normally. What happened?

    • So-called arrested ear development can be the result of corn plants suffering from stress–perhaps lack of water, or lack of nutrition. Water regularly (the root zone must stay moist at all times) and feed the plant compost tea or sidedress with aged manure and/or aged compost. Another possibility: the ears are present but not yet developed; give the plants more time. Spacing can sometimes cause plants to fail to pollinate; mature corn plants should be spaced 15 to 18 inches apart in all directions–corn planted too close will not form ears and pollinate. Finally a “bucketful of assorted seeds” may mean you have several varieties with differing days to maturity–enough time may not yet have passed. Since the supplier was a “sustainable seed supplier” we can assume your seed is open-pollinated and will grow true; but if it is seed from hybrid corn, you may never see ears. If there are multiple varieties in the bucket, planting a mix of varieties may stymie pollination as plants of differing varieties flower at differing times (tassels are not always readily visible). Given all this: water well, feed, and wait. If you do not have a crop this year, next year ask the county extension agent for a list of locally recommended corn varieties and plant one.

      • Thanks, Steve. I now have tassels and ears coming out all over the place, so being patient was good advice. I was late getting the patch planted, and it is apparently a late-season corn. Now I have stalks approaching twelve feet tall, but some are starting to fall over, even though they are shielded from the breeze by the old foundation wall. They are still green though, so I may yet get a few ears from those as well. Thanks for the advice.

  5. Steve, Our corn was beautiful this past year. Full ears and strong stocks. Yet it was lousy tasting, bland and soft. Like it had been soaking in water for days. Even fresh off the stalk it was like this. This was a new garden and our first crop of corn. Thanks for any help.

    • Tasty corn is a matter of timing. Once the ears are filled out an mature, pull back the husk and pop a kernel with your thumbnail–milky juice means the corn is just right and ready for harvest; watery juice means the corn is a few days immature. If the fluid is watery, wait a few more days. If the fluid is gummy you’ve waited too long.

    • Be patient. The the ears will appear in time. In the meantime, spread well-rotted compost around the past of each plant to give it plenty of food.

  6. This is my first year growing corn and I only planted a dozen stalks. So far 2 of the ears of corn have large green/gray growths growing from the top of the ear. What is this caused by? How can it be prevented on other ears?

    • Hi Heather, A photo might help me on this one. Green-gray could simply describe the feathery tassels; these are the pollen producing flowers and they do not need to be removed. If the tops of the ears have white-gray galls, that is corn smut, a fungus that grows on ears–the galls can be removed and in the future plant resistant varieties. Corn ears will sometimes look malformed when pollination has been incomplete; each tassel is connected to a kernel and if pollination does not occur the kernel will not mature.

    • Brownish-red leaves may be rust disease. Rust will ultimately cause corn leaves to turn yellow and drop. Pick off infected leaves and compost them. Be sure you are watering at the base of the plants. Rust fungi can over winter in crop debris so be sure to clean up the garden thoroughly after harvest. Look for rust resistant or tolerant varieties next season.

  7. My corn plant is still growing but not ready to produce the ears yet. There is larvae inside the leaves. Do you think a hot sauce solution would rid of the Armyworm larvae.

  8. I’m growing sweet corn, and where the ears of corn should be growing, more corn stalks are growing. I’ve never seen this before. Has anyone else had this problem?

    • It sounds like your cornstalks have not tassled at all. Here are some possible causes: (1) Too much nitrogen in the soil resulting in green growth; not enough phosphorus to promote root and ear growth; (2) Poor irrigation; corn is shallow rooted and depends upon regular watering; inadequate water will cause plant stress; (3) Bacterial wilt, root and stalk rot, and viral and fungal diseases can leave the plant weak and unable to produce ears; (4) Nematodes eating the roots resulting in poor uptake of nutrients. If it is one of the first two then you should be able to fix the problem; add a organic fertilizer high in phosphorus around each plant and increase water.

  9. I recently bought six ears of corn and when I peeled them I found three of the ears had this golden brown dust like on them around the kernals. Like somebody had put seasoning salt on them, what is it. I threw them out. More at the base of the ear.

    • Assuming there was no insect damage to the ears of corn, the golden brown dust that you found on the ears was likely either spent anthers–the pollen-producing part of the corn tassel–or the pollen itself. Remember that corn produces individual male and female flowers on the same plant. The tassel represents the male flower of the corn plant; the male flower includes the anther.

      Each tassel produces from 2 to 2.5 million pollen grains–each grain of pollen is nearly microscopic, spherical, yellowish- or whitish almost translucent. Each pollen grain contains the male genetic material necessary for fertilizing the ovary of one potential kernel.

      Pollen shed usually begins in the mid-portion of the central tassel spike and then progresses upward, downward and outward over time. Once the pollen is shed, the anther–the pollen producing part of the tassel–will dry up and drop. Spent anthers eventually drop from the tassel and are sometimes mistaken for the pollen when observed on the leaves or ground.

      You can use a damp clean terry washcloth to remove the tassels and pollen dust and dried anthers from the ears.

    • Your description sounds like corn smut a plant disease caused by a pathogenic fungus. The fungus forms galls on all above-ground parts of corn. It usually causes normal kernels to become large and distorted–galls or tumors that look somewhat like mushrooms. The fungus spores are blue-black having a scorched appearance. Corn smut in Mexico is known as huitlacoche–a food delicacy eaten, usually as a filling, in quesadillas and other tortilla-based foods, and soups.

      You can control corn smut by applying a fungicide as soon as it is detected. You can prevent the spread by removing infected corn from the garden and disposing of it. Plants whose roots have been injured are sometimes prone to infection.

    • You can use an eyedropper to squeeze a few drops of vegetable oil into the top of each ear–thus suffocating the caterpillars. You can spray your plants thoroughly with a homemade horticultural oil spray as well: add a tablespoon of liquid soap (not detergent) to a cup of vegetable oil; put a tablespoon of this concentrate in a gallon of water to make your spray.

  10. I followed all the advise on the packet and the sweet corn plants grew very tall and looked promising, but very few cobs have developed to a mature state even after 19 weeks. When I looked at a local field of maize sown at the same time, the rows were 70 cm apart and the plants 10 – 15 cm apart and all the cobs were full and ripe, so the spacing advise I followed would seem to be wrong. Can you help please?

    • A steady supply of moisture is critical for the full development of corn–especially from the time the tassels appear until the ears are ready to pick. Corn is part of the grass family–so you may need as much as 2 inches of water per week if the weather is warm or hot. A soaker hose may be helpful, as well you may want to mulch with straw or grass clippings to slow soil moisture evaporation. Corn needs plenty of nutrients–sidedress with aged compost. Because the cops were full, it would seem there was no problem with pollination.

    • Assuming you are not growing a miniature or midget corn variety, add aged compost to your corn planting area to make sure the plants are getting a wide range of nutrients. Do not use a fertilizer too heavy in nitrogen–a 5-10-10 organic fertilizer should be good. Keep the soil evenly moist, do not allow it to totally dry out in the root zone.

    • Sweet corn kernels left on the plant too long will become hard and starchy. It is important to pick corn about 20 days after the silk first appears. The silks will have turned brown but the husks will still be green at harvest. Each stalk should have at least one ear near the top and often another ear lower down on the stalk. The lower ears are usually smaller and mature a little later than the ones at the top of the stalk. To know it is time to pick, puncture a kernel and look for milky liquid inside. If it’s clear, the kernels aren’t quite ready. If there is no liquid, you’ve waited too long.

  11. Help! My corn is already showing ears and it’s only 8-10 inches tall?
    I would love to send a picture but I couldn’t figure out how. I would appreciate any help I can get. Thanks in advance!

    • Check to see what variety of corn you have planted. There are small growing varieties. Just continue to care for the plants–keeping the soil evenly moist and let Mother Nature take care of the rest.

  12. I have problem that the base of ear have no full kernel.
    Another problem is multiple ears around ear. please explain for that
    Regards with thanks

    • Corn ears that do not fill out are likely suffering from incomplete pollination. You can hand pollinate corn when the tassels are fully open and beginning to shed the yellow pollen. Snap the tassels off a few stalks and use them like feather duster–dusting over the emerging silks at each ear. Make sure you dust all of the ears. The best time to do this is in the morning between 9 and 11 am.

  13. This is the 2nd year growing corn here in Southern California and we are having the same “problem” as last year even though we really prepared the soil well this year. The problem is that the plants don’t grow more than 3 or 4 feet and then the silks appear and this results in very small ears. What might we need to adjust?

    • Drought–too little water–is the he most common cause off corn silk problems. Silks have the greatest water content of any corn plant tissue and are the most sensitive to moisture levels in the plant (and soil). Try to keep the soil evenly moist at all times–increase the amount of moisture holding soil particles by adding aged compost to the planting beds and by mulching with compost around each plant.

        • Weather and temperatures can delay the maturation of plants; days to maturity list on a seed packet are optimal but not always realistic. Give the plants a few more weeks to fill out. If the ears do not fill out, then pollination was insufficient. Each tassel must be pollinated. It is important to plant corn in blocks so that pollen can easily float on the breeze from one plant to the next.

  14. Can not find my question or a reply so will ask again . I have corn that is growing fine but there absolutely no ears on them. Should I pull them up and plant again or can I use something to promote the ears on? Please help me!

    • Here are a few reasons corn may not produce ears: (1) lack of water can stress corn plants–make sure your crop gets moisture every few days; if the soil is dry the leaves will curl; (2) too much rain can wash away pollen affecting pollination; (3) too much nitrogen in the soil can result in green leafy growth but no or few ears; (3) spacing, be sure to block plant corn to encourage wind pollination–at least 4 rows side-by-side, each row just a few feet apart; (4) pests can attack roots and disrupt the flow of nutrients and moisture to the plant affecting pollination and ear growth.

      Read more at Gardening Know How: No Ears On Corn Stalks: Why Is My Corn Not Producing Ears http://www.gardeningknowhow.com/edible/vegetables/corn/corn-not-producing-ears.htm

  15. My first year to try to grow corn. It grew beautifully, tried first ear 5 days BEFORE it should have been mature. Every cob is starchy. Too starchy to eat. Even less mature cobs on less sun side of garden! I’m very disappointed. What went wrong?

    • It is important to harvest sweet corn at the proper stage of maturity. The time to harvest is called the milk stage–when the juice in the kernels appear milky when punctured with your thumbnail. Sweet corn is in the milky stage for a short period of time so you want to check the ears frequently. During the milk stage, the unhusked ear should feel firm; kernels at the tip should be full; silks emerging from the ear should be brown and dry. Once picked, the sugars in an ear of corn begin to turn starchy quickly–use ears within 12 hours of picking. All of this said, the sugar in just ripe sweet corn can become starchy while still on the plant in very hot weather.

  16. I’m looking for an answer to my dilemma. It is kinda funny but my horses snapped off the top of my corn stalks, the corn had not tassled yet. I’m wondering should I till it under or let it keep growing.
    Thanks

    • Multiple stalks from a single corn seed is not a problem and trimming away stalks is not necessary. Coleoptile is the name for the pointed protective sheath covering the emerging shoot in monocotyledons such as corn. The coleoptile grows from the seed and then emerges from the soil; from there the corn stalk develops and grows upward. Cold soil temperatures at the time of germination or crusted soil and other environmental factors can cause coleoptile damage and unconventional growth–including splitting. The plant can survive all of this and grow on healthy.

    • If birds did not steal your seeds, then a vole, mouse, rat or other close to the ground creature may have. You can spray garlic or pepper solutions around the garden–look for tracks to see where the critters are coming from.

  17. I was growing a garden at the school where I worked. The parents wanted to take it over during the summer. Now the husk and leaves are brown. What should I do?

    • You can harvest the corn that is on the plant–but if the husks are brown, it is likely these ears will not be edible. You might be able to save the seed for planting again next spring. It sounds as if the plants either did not get enough moisture, or that they matured and have gone past harvest time.

    • Harvest the corn and grind to use as corn meal. I work in school gardens and we always use our sweet corn, popcorn and flour corn this way. The corns all have a slightly different taste, but are all delicious! Kids are not in school when sweet corn reaches the milk stage (unless you plant it yourself after school ends) and honestly I think the grinding of the corn and making bread is way more interesting for the students than the sweet corn would be anyway. I usually have the students take the dried kernels off the ears. We then grind it in my Kitchen Aid flour mill (I’d love to have a hand crank mill, but they are really expensive!) And bake into bread. To incorporate even more from the garden the corn bread batter can be layered in the loaf pan with peppers, onions, herbs and optionally cheese. This activity is really one of my students favorite fall activities!

  18. One of my corn stalks was broken in half by a cat, will it re grow? The leaves are still green but the stalk was severed at the base, any chance? Ta.

    • If the stalk was severed at the base, the plant may soon wither and die. If it was damaged further up the stalk, it may regrow and produce ears of corn–if there are enough warm days left in your growing season.

  19. I planted a little late and I have tassles, but no corn yet. I only have a dozen and I think you would call this block planting. My question is, can we help the pollination buy cutting some tassle and sprinkling on the corn?

    • You can hand pollinate corn by snapping the tassels off a few stalks and then dust over the emerging silks at each ear. Hand pollinate for about a week.

  20. Hi Steve, I have some stalks that have grown tall and have tassels, but then I have other stalks that are only a foot tall. The corn is all the same and it was planted at the same time. They appear healthy. Any suggestions? Thanks, Mike

    • Stunted corn plants may be the result of poor moisture and nutrient uptake. Before you plant for next season, add plenty of aged compost or planting mix to your growing beds–aged compost holds moisture and nutrients for even uptake by plant roots. Also add a 5-10-10 dry organic fertilizer to the beds before you plant.

    • There are some simple reason why corn leaves turn purplish or have purple streaks. The two most common reasons are (1) your corn may be a hybrid variety; (2) temperatures are cool. The purple color can be an expression of genes for anthocyanin pigment formation. This color trait is inherited in the hybrid or variety. Many corn varieties have this gene. The color is genetic and may be induced by nighttime air temperatures below 50 F (10 C) when day temperatures are above 60 F (15 C).
      Corn plants can outgrow the coloring; this usually happens when temperatures warm. There is a third reason corn leaves can turn purple and that is a phosphorus deficiency. Adding phosphorus to the soil after the leaves are already purple will not turn leaves green–but it may prevent future crops from having purple leaves. Use an organic 5-10-10 fertilizer to add phosphorus to the garden. In the off season add plenty of compost to your garden beds to make sure they are well drained and to add organic phosphorus to the soil. In the meantime, your corn with purple leaves is edible.

  21. Great site. We grew some sweetcorn (In Wanganui NZ) but did not harvest all the produce. We now have plants with dried husks and ears. Can we use these ears to grow more corn this year?

    • You can shuck the dry ears and save the seed and plant it again next year IF the variety you are growing is NOT a hybrid. If you are growing an open-pollinated variety (non-hybrid) you can save the seed, sow it next season, and it will grow true to its parents. Hybrid seed commonly does not grow true but reverts back to one of its parents.

  22. OUTSTANDING info Steve. Thanks for taking the time to share your knowledge and to repeatedly answer questions. you deserve a round of applause(or a bushel of CORN! 😉

  23. Very good information here. Thanks for writing it up. I’ll be checking here as my corn progresses, hopefully I can get a good crop this year.

    Lorian Bartle

    • It sounds as if a four-legged garden marauder or perhaps birds are harvesting the seed for their own use. When you plant the seed, put down a light weight plant blanket or row cover over the seed bed. Be sure the edges of the cover are tucked into the soil or lay boards along the edges so that the culprits don’t get under. A loose fitted floating row cover can remain in place until the seedlings are several inches tall.

  24. I have 8 thirty foot rows of sweet corn and I planted the seeds 4-6” apart in each row. All my corn is currently sprouting and looking good but I have 2-3 plants growing in each hole and in the last 3 rows my kids managed to throw 6-7 seeds in each hole so now I have 6-7 plants that have sprouted in each hole of the last three rows which brings me to my question. How do I properly thin out the corn in each individual hole to just one plant? Do I pick one of the plants and take scissors and cut the others? Or do I pull the plants out by hand and risk damaging the roots of the one I keep?

    • When corn ears do not fill out there can be a few possible causes: (1) poor pollination; this can be caused by weather which affects tassel and pollen development; replant if you suspect weather was the issue; (2) insufficient soil moisture; corn is shallow rooted–keep the soil evenly moist throughout the season; (3) lack of nutrients; side-dress plants with an organic all-purpose fertilizer.

  25. Hello, I’m growing Silver Queen corn on the Cob, my problem is 1. The leaves are brown, I see some purple streaks and some spots. 2. My ears are small and the cob is not firm but very soft. I’m growing in containers also. What am I doing wrong. Do i need to start the process over with a different type of corn on the cob. Thank you.
    Hot in millington TN.

    • The streaks on the leaves of your corn are likely a sign of a fungal disease known as corn leaf blight. There are two types of leaf blight Northern and Southern. The control and treatment to the same for both types: (1) remove diseased leafs and place them in the trash; these leaves are infected with fungal spores which can spread to other plants; (2) spray plants with a fungicide (a simple fungicide is compost tea which is easy to make) or you will find fungicides at the garden center; (3) increase air circulation around your plants; (4) do not get water on the leaves if possible; (5) at the end of the season remove all diseased material from the garden plant leaf blight-resistant varieties of corn; (6) in the future, plant disease-resistant varieties–seed packets should note if the variety is resistant to leaf blight. Because your plants are in containers, be sure that you are not over-watering; you may need to use a moisture meter to make sure the soil at the bottom of the container is just drying out between waterings. Reduce the amount of nitrogen you are giving the plants; this may account for the ears not being firm. If you have enough season left where you live, start new plants now.

    • Corn has male and female tassels (flowering parts) on the same plant. Male flowers produce pollen. Pollen is dispersed through pores at the tips of the anthers on the male flower. Pollen is shed along the length of the tassel (the tassel is a collection of many flowers) starting in the middle and progressing down and up the tassel over the course of about eight days. When the pollen is shed the anthers drop from the tassel and the pollen shedding work of that tassel is finished. In time the tassel having done its work will dry up. If you are interested in more detail visit the agronomy pages at Purdue University https://www.agry.purdue.edu/ext/corn/news/timeless/Tassels.html

  26. I purchased some corn, and couldn’t deal with it immediately, so I put it in a container of water to keep it moist. An hour later when I removed the ears, there were about 8-10 1/2 inch colorless worms on them. They weren’t there when I husked them. I never saw this before, but then I never soaked corn on the cob before, either. What was this? Thank you for your help. I haven’t purchased any since, and am afraid to.

    • The colorless worms that were hidden in the ear of corn were likely the larvae of the corn earworm. Earworms can grow to an inch or longer as they feed on the ears of corn; they are light yellow, green, or pink. The adult is a yellowish-tan moth that lays its eggs in the silks of the corn. When the larvae hatch they feed on the corn seeds and wiggle their way down into the ear. Of course, they are quite small to start but eventually will reach an inch or even two in length. Five drops of vegetable oil applied to silks after they have wilted will kill the earworms. Soaking the ears in some lightly salted water will do the same.

  27. Hi, my husband has been told by another allotment user to leave his sweet corn roots in the ground after harvest as it puts nitrogen back into the soil. Is there any truth in this, please?

    • Researchers at the University of Wisconsin–Madison, the University of California, Davis, and Mars Inc., have identified varieties of tropical corn from Oaxaca, Mexico, that can acquire a significant amount of the nitrogen they need from the air by cooperating with bacteria. This discovery is similar to what we already know about legumes–that with the help of soil bacteria nitrogen can be fixed in the roots and so legumes don’t need additional nitrogen. The researchers found that the corn from Oaxaca can get 30 to 80 percent of its nitrogen in this way–environmental factors like humidity and rain played a role in the success of nitrogen-fixing. The researchers have not yet found what trait the Oaxaca corn has that allowed nitrogen to be fixed. Once they determine the trait then they will work to breed that trait into commercial corn cultivars–which gardeners could then buy from seed companies. Your husband can ask his fellow gardener if this is what he was referring to or if there is other research he may know about. Leaving the roots in the soil will contribute to the organic matter in the soil, to the friable nature of the soil–which are garden benefits. Corn is a member of the grass family and grass debris is commonly rich in nitrogen; perhaps this is what the gardener was referring to.

  28. I now live in the Philippines, my son sent me different seeds to grow a garden, I received sweet bantam corn seeds, planted as described, now my plants are not very high only two feet high, the ears a nice but the silks are already coming out, shouldn’t the plant be at least five feet tall. They don’t sell fertilizers here so I make my own with vegetable scraps, Epson salt and a little bit of ammonia, it works well sometimes I get sea weeds and mix it with my veggie scraps, my long beans, cucumbers, okra, basil, spinach are all doing well but my corn stalks are really bantam not very high, I also bug spray my plants with chicken wash soap, we have lots of ants here specially the red ants, my garden soil is very clay, so I mixed all of the soil with rice husk, so that the soil does not become to hard, any suggestions?
    Thank you

    • Bantam corn usually matures at 5 to 6 feet tall. Corn growing in heavy, clay soil–that is compacted soil–can become stunted and not reach its full height. Add aged compost and well-rotted manure to the soil; this will break up the clay. You can also sprinkle gypsum across the planting bed to help break up heavy clay soil. Planting on mounds or raised beds will also lift the roots above the clay. Corn, which is shallow-rooted, demands well-drained loamy soil. Stunted growth may also be caused by a lack of nitrogen in the soil; it sounds like your home-made fertilizer is rich in nitrogen.

    • There are a few reasons corn can be stunted: (1) night or day temperatures have not warmed; day temps should average 70F or warmer; night temps not cooler than 60F; if the weather warms the plants will grow; (2) corn rootworms; drench the soil with parasitic nematodes; replant in a new area; (3) maize dwarf virus; pull and destroy the plants; plant resistant cultivars; control aphids which spread the virus.

  29. Steve,
    I have four raised beds (3×5) in a row. The two center ones are planted with a 65 day corn. The two outer ones are planted with different varieties of 80-90 day corn, planted a week apart. I could bag the ears and tassels and hand pollinate-there’s not much so it’s doable. But I had a silly idea: I have large tree bags (white) and I was wondering if I could set up a frame and cover the bed to contain the pollen. The bags let in 90% of the light and I water the beds daily so no concern for rain. I’d get under there and hand pollinate to compensate for the lack of breeze and it would only be up for the pollination interval. Is this as goofy as it sounds? I really like the idea of different varieties in my small garden and I thought this might be a convenient way to keep the varieties true.
    Thanks for any advice-your site and book have been very helpful to me.

    • You could certainly do what you propose if you don’t mind hand pollinating. The effect of cross-pollination on this generation of corn may be minimal; some ears may not grow as large. The next generation (if you save seed) will not grow true if there is cross-pollination. If you are purchasing new seed each year, you don’t need to hand pollinate. Rather than cover each bed, you could use your row cover to erect a barrier between each bed–this will cut down on pollen making it from one bed to the next.

      • Thank you for your reply. I don’t save seed so no worry there. I’d read some articles stating that the sugar-enhanced varieties get starchy when crossed with one another and it’s worse when there’s a dominant variety nearby and if I can get the space prepared I’m putting in popcorn downwind. I’ll try to sow this as late as I can manage and if the se gets on the popcorn it shouldn’t bother it.
        I like your idea better-easier to do and less of an eyesore. Since the beds are so small I like to give the corn I do get every chance I can to produce.
        Thank you so much for this site and answering your readers’ questions. I always get the best, most clearly stated information from you. It’s made me a better gardener.

  30. We harvested several wars that were sweet and perfect. Now the remaining ears appear to be incomplete in their growth and the leaves on the plant are turning brown. I feel like our problem was water related. Will the remaining ears grow or should we forget about them?

    • Incomplete ears–that is ears without a full complement of kernels–has not been fully pollinated. If the leaves have started to brown, harvest what you have and use the parts of each ear that have filled out. You likely have enough season left to plant a new crop or more than one crop. Take a look at this article for more on pollination:
      https://harvesttotable.com/how_to_grow_sweet_corn/

  31. We planted corn fields early may spontaneously as something to do in a tilled area but no compost/ fertilizer. 8 50 ft rows and 16 25 ft rows. It’s 8 to 10″ tall now. There are some purplish edges on leaves now in some plants. What blend of fertilizer for side dressing should we use? We use soaker hose to water.

  32. My first time growing corn in grow bags. In one bag the middle stalk and deep inside leaves, there are lots of little black speck, I removed some to see if they moved but they were all smoosh. No movement. Had a couple of ants on the stalks. Should I pull them? What can I do to save them? Thankyou for your advice

    • If ants are near the black specks, it is likely the specks are scale or aphids. Spray with an all-season horticultural oil to smother the insects. I the black specks are fungal, the soil will smother the fungus spores as well. If you have tassels on the corn, be careful not to spray the tassels.

  33. Our corn growth was stunted and we know why. They have red and purple on the outside of the corn. My question is Are they still edible?

    • Forms of corn ear rot and mold can produce toxins and should not be eaten. Consult with the nearby Cooperative Extension Service to test for corn eat toxicity.

    • Feed the corn with an all-purpose fertilizer, 10-10-10. Scratch the fertilizer into the soil around each plant then water thoroughly. You can apply the fertilizer again in about three weeks.

    • After tasseling pollination will occur, this will cause the kernels to grow to maturity which is perfectly normal. However, if the kernels are replaced by large, fleshy gall filled with black powder, that is the disease corn smut; remove and destroy ears or galls as soon as you seed the disease.

  34. After growing corn successfully for at least five years, the last two seasons have brought new problems. This post was extremely helpful and I plan to do a post on my problems this year and link to your excellent post. I do depend on your well-researched and experience-rich advice. Thank you!

  35. My corn stalks have started to bend at the joints. I have ears and tassels and they appear to be doing well. I am just wondering why this is happening and if it is bad for the stalks. I have 16 stalks, some split when they were growing so it looks like I have more. There are ears on all of them and I believe I’m getting close to harvesting. Is this something I need to worry about? They are strong at the joints, they are not falling over, just a couple of them are going at an angle. This just happened over the past week or so. Thanks for any info.

    • Corn stalks that bend may not be getting enough water; the watering could be uneven, dry-wet-dry; Feed the plant with a 5-10-10 fertilizer and keep the soil moist. Place long bamboo canes next to the stalks to help keep them upright until the plants gain strength.

  36. Hi all, I grew blue corn and my close neighbor grew sweet corn. We now both have a lot of ears with yellow and blue kernels. If I plant the blue kernels next year will I still get blue corn or will I get his hybrid? Thanks

    • Insects, birds, and other varmints may find seedling leaves tasty. If the tops of the seedlings have been nipped off, they will likely not regrow. The surest strategy is to resown the seeds and cover the seedbed with a floating row cover which will exclude many insects and birds. Once plants get 4 to 6 inches tall, you can remove the cover.

    • Feed the plants with a dilute solution of fish emulsion every 10 days. Check the variety you are growing; you may be growing a miniature variety that will not put on much more height.

  37. I have a very small field for self picking of sweet corn eaten off the cob in the field. When all has been eaten how do i remove the dry storks in easiest manner?

    Or is it best to leave them in field?

    • Corn is shallow-rooted; you can remove it easily. The stalks do not compost quickly. Chop them up if you plan to put them in the compost pile or if you plan to turn them under to decompose.

  38. Hello,

    I have a question regarding corn smut. I’ve just found two galls growing from the bottom of the stalk of my only corn plant. Given the galls are still withish in color (no black in sight) should I get rid of the entire corn plant or just carefully remove and dispose of the galls?
    My corn plant hasn’t produced any corn yet, but other than the two galls I’ve found, the rest of the plant seems healthy enough.
    Thank you.

  39. Hello, I grew my corn seed in peat pots and then transplanted half into a raised bed of compost in my glasshouse and the other half into a raised bed of topsoil outside the glasshouse. All the raisedbeds outside have the same topsoil; All my parsnips and carrots, leeks and onions and beetroot are growing really well. However the corn I planted outside in the same topsoil has almost gone white and is very sickly looking ; as opposed to the greenhouse corn which is lush and dark green and growing vigorously. My first obvious thought was that the soil is deficient as it is only topsoil, however, all the other produce is growing just fine in it. i have sprinkled dried stable manure, worm castings and sheep pellets amongst the plants outside three days ago, will this be enough to rescue the corn? or shall i be better to just rip it out and start again? This is mid spring in new zealand as i write this question. sorry it was sooooo long. I look forward to your advice 🙂

    • If the problem was a lack of nitrogen, the organic fertilizers you have added should green up the plants in short order. If the plants do not turn around in 5 days, plant again. Make a checklist of other possible problems: (1) night temperatures dipped; (2) plants were over or under watered; (3) herbicide drift; (4) an animal disturbed the planting area; (5) a chemical or synthetic fertilizer hit the plants. A bit of detective work may under the cause.

  40. My daughter and I decided to try corn this year. We prepared our raised bed properly. Have about 20 stalks. They looked great but now are all falling over at the base. Not seeing signs of corn grubs. It is ok just to prop these up? Is there another issue I should be looking at?

    • Corn is shallow-rooted and it will appreciate any support you give it. You can mound up more soil around the base of the plant to help the roots get a better foothold. You can also place long supports such as bamboo stakes next to each plant and tie them in with elastic garden tape. Corn planted close together in blocks will often support each other.

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