Home GardenOrganic Vegetables A Vegetable That Grows On The Ear: Sweet Corn

A Vegetable That Grows On The Ear: Sweet Corn

by a Friendly Gardener
Harvested corn

Often referred to as the three sisters, beans, squash, and corn, Native American tribes interplanted these three vegetables as companion crops because they do so well together. Sweet corn is a favorite in the North American diet with its white, yellow, or bi-colored juicy kernels. To cultivate corn, however, you need a long growing season that is free of frost.

A native of North America, it is thought to have been first domesticated for cultivation in Mexico, and from there it spread. Nowadays corn is a staple used in many forms and is generally cultivated on an industrial level, but that doesn’t mean that it can’t find a place in your garden.

A member of the Poaceae or grass family, it needs the wind for pollination purposes and for this reason is better cultivated in a block formation as opposed to long rows.


Corn Types and Classifications

Sweet corn

Varieties of corn include those for early, mid, or late harvest seasons. The early type will mature the fastest while the late harvest corn type will require the entire growing season to reach maturity. To achieve the most, you can plant all three types for a constant supply. Hybrid sweet corn also comes with four principal classifications that indicate sweetness:

  • Sugary (Su)

A sweet variety that is stress-resistant, but sugars will turn to starch quickly, so this type needs to be eaten as soon as you pick it. Avoid planting near synergistic or shrunken varieties.


  • Sugar enhanced (se)

This is a sweeter variety than the sugar kind and the sweetness will remain several days longer after harvesting. Avoid planting near shrunken varieties.


  • Shrunken (sh, sh2)

Also referred to as super sweet, this corn will be two to three times sweeter than other cultivars. Sweetness will remain for a week after harvest. Kernels tend to be crunchier in texture. These cultivars should not be planted near other corn types.


  • Synergistic (sy)

These kinds of corn varieties are a hybrid of the sugar enhanced type and the sugar or the shrunken offering the best quality with tender sweet kernels. Some cultivars can last up to a week after harvest. Avoid planting near shrunken or sugary varieties.

An important thing to keep in mind is that cross-pollinating is common, and should the wrong kinds of corn cross-pollinate, quality will be compromised with kernels potentially tough and starchy.


Planting Sweet Corn


Select a Location

Corn field

Corn can be finicky when it comes to soil and pollination. Choose a plot where you can plant at least four rows deep instead of in single rows to ensure pollination. This plant is not pollinated by bees or other pollinators but by the wind.

Soil should be fertile with organic matter, so ideally, tilling your soil in autumn with aged manure and then letting it overwinter, will provide you with a great soil bed, to begin with, come spring. If you cannot do this, till the soil with aged compost before sowing.

Soil should be well-draining but retain moisture because corn plants tend to be heavy drinkers.


How to Sow Sweet Corn

Corn on the cob

To enable germination, moisten your corn seeds and then place them in moist paper towels. Place everything in a plastic bag for 24 hours. Seeds should be sown approximately two inches deep and six inches apart, ideally in four rows that are distance three feet from each other.

Once you have sown seeds, you can fertilize them with a quality 10-10-10 vegetable fertilizer. If you feel your soil is rich in organic matter, it is not necessary to fertilize. Water sown seeds thoroughly.


Sweet Corn Care


Thinning and Weeds

When seedlings appear, wait until they are about four inches tall and begin thinning your plants. Maturing plants should be thinned to eight to twelve inches apart. Weeds that appear should be removed but when doing so, take care not to damage your corn’s root systems.



Corn must be watered well because root systems are shallow, and they will become stressed and suffer if the soil bed becomes too dry. Plan on providing an inch of water weekly including any rainfall. If, however, your soil bed tends to be sandy, you should water more often, or if the growing season is exceptionally hot. Mulch can assist in reducing evaporation for moisture retention.



When your corn stalks reach about eight inches in height, side-dress them with fertilizer that is high in nitrogen content.  When stalks reach approximately eighteen inches in height, repeat this side dressing.



To help stalks grow straight up, if your area is subject to wind, create mounds of dirt around the base of the stalks when they reach a foot in height.

Offshoots at the base of the plant can be left as they will not interfere with the main stalk’s growth.


Pests, Diseases, and Problems

Corn has its share of tormentors.



  • Corn Earthworms

Kernels and silks will appear eaten. Remove any larvae. Apply vegetable or mineral oil to ear tips.


  • Cucumber Beetles

These spotted pests will munch holes in the foliage while larvae will eat roots. They also are carriers of bacterial wilt. Remove manually, use row covers, and mulch heavily. Destroy stalks that show signs of bacterial wilt.


  • Cutworms

If your plants are wilting and stems are severed above or below the soil surface, cutworms are to blame. Entire seedlings can vanish. Remove any manually. Use row covers or place 4-inch-wide collars at the base of plants at least two inches deep into the soil.


  • Earwigs

Foliage will have numerous small holes and the silks will be eaten. Place a tuna can with one-half-inch of fish oil into the soil with the rim just visible.


  • Flea Beetles

These critters leave lots of tiny holes as if from birdshot in foliage. Use row covers and mulch heavily.


  • Japanese Beetles

These pests will damage kernels and silk, grubs will eat the roots, and foliage will be eaten to the point that only veins remain. Remove manually. Use row covers.


  • Wireworms

Stunted or wilted growth and severed seedlings are indicative of these worms. You can trap them with holes dug every five feet and filled with germinating potato pieces or beans. Cover with soil or a board. After a week, uncover and destroy collected worms.



  • Deer

If stalks are chewed, you’ll know the local deer have come for a meal. An 8-foot fence is ideal. Scatter items with human scent around your plants.


  • Raccoons

If stalks are broken and ears half-eaten, a local bandit is visiting your plants. Place human-scented items around your plants.



  • Anthracnose

This fungus will appear as dark spots on stems and as yellow, purple, brown, or black spots on foliage. Spots may turn gelatinous and rot the stalk. All infected plants should be destroyed.


  • Downy mildew

This fungus will leave yellow spots on leaves that then turn brown. Cottony growth will be apparent on the leaf undersides. Avoid overhead watering, remove infected foliage, and ensure air circulation.  Consider resistant varieties.


Harvesting Sweet Corn

Growing corn on the cob

If the climate is warm, corn will mature faster. Once silking appears, your corn should ripen for harvest in 15 to 20 days. It may do so sooner if it’s hot out. Ears should appear rounded or blunted but not pointed. Tassels should be brown and kernels milky. You can test by pulling down a strip of husk and piercing a kernel with your fingernail. If it is milky, harvest. The milky stage is very brief and will last for a couple of days, so keep an eye on it. Once the milky stage has passed you can harvest but the corn may not be as sweet.

Stalks with various ears will see the upper ears mature before the lower ones. Pull ears downward when harvesting and twist to remove.

Generally speaking, corn should be cooked or preserved as soon as it is picked. “Su” varieties begin to lose sweetness after harvesting. Should your immature corn crop suffer a frost, the cobs may be damaged and the taste ruined. Plants can also die from frost damage.


Storing Corn

Yellow corn

Kernels can be removed from the ears and frozen.

  • Harvest ears
  • Blanch small ears for approximately 7 minutes in boiling water, then place them in icy water (9 minutes for medium-sized ears and 11 minutes for large-sized ears).
  • Ears should sit in ice water until they cool (usually the same amount of time as blanched in boiling water).
  • Using a sharp knife, remove kernels from the cob.
  • Place kernels in a zip-top freezer bag, seal, and freeze.

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