How to Grow Corn

Around 10,000 years ago in what is now Southern Mexico, subsistence farmers began experimenting with a scrubby wild grain called Teosinte. Over generations they selectively bred for larger and larger starch-filled kernels until they developed the ubiquitous grain that we now call corn. Corn gets a pretty bad rap in the U.S. because of its use as a sweetener in the form of high-fructose corn syrup, but as a whole grain it has a similar nutritional profile to whole wheat.

Whole grain corn makes an excellent staple crop and it’s eaten daily by hundreds of millions of people around the world. In our household corn is a regular feature on the dinner plate in the form of tortillas, cornbread, grits, pupusas, and more. We dedicate significant amounts of space in our subsistence gardens to grain corn where it grows alongside its sisters, beans and squash. If you’re working towards producing more of your own food in North America, this is a borderline necessity in your veggie garden. Read on to learn all you need to know to grow a successful corn crop this year!

Types of Corn

The fresh sweet corn you eat at summer cookouts is what comes to mind for many Americans when we hear the word "corn," but it’s just one of many varieties. The four primary types of corn are flint, flour, dent, and sweet.

Flint corn is a dense, hard-hulled variety bred for short Northern winters. It’s packed with starchy carbohydrates and protein. Maybe you've never heard of flint corn before, but you’re probably already familiar because this is where popcorn comes from. This type of corn is also excellent for grinding into grits and cornmeal or simply throwing into stews whole and cooking for hours.

Flour corn is a soft-hulled variety bred for drier, hotter conditions in the Southwest. It has a similar nutritional profile to flint corn. This is the most common type of corn used to make corn tortillas, tamales, pupusas, and other staple foods.

Dent corn is actually a cross between flint corn and flour corn and provides you with a bit of hybrid vigor. The nutritional profile is similar to the other two, but it forms massive ears and produces more calories per acre than any other grain crop on Earth. This is the variety that many of our chemical companies have modified slightly so they could patent its DNA—funny when you think of the 10,000 years of work that went into it before they came along. Many heirloom varieties like Wapsi Valley, Bloody Butcher, and Hickory King are still available in their original forms.

The final type, sweet corn, is primarily different from the others in that it is picked and eaten unripe. The sweet milky liquid that bursts out of sweet corn kernels is what dries down into a starch in the other types of corn. As the name implies, sweet corn is bred to have a very high sugar content and basically nothing else. Nutritionally it is not quite as valuable as the other types of corn, but it makes a delicious snack nonetheless.

Growing Conditions

Depending on the type of corn you’re growing the days to harvest will vary widely, but every type of corn likes it hot. Most information you’ll find online says to wait to plant your corn seeds until the soil has warmed to 50 to 60 degrees Fahrenheit. Assuming you’re one of the many gardeners who doesn’t own a soil thermometer, this probably isn’t very helpful. As a rule of thumb, the soil will usually be warm enough for your corn to successfully sprout around the average last frost date in your growing zone. Plant your corn where it may grow with full sun exposure, and depending on the temperature it needs about an inch of rainwater or irrigation per week.

To grow conventional blocks of corn, space your plants about 6 to 12 inches within the rows and 2 to 3 feet between the rows. Try to maximize the number of rows to form as much of a square as possible—this will help with pollination later in the season. To grow traditional mounds, as used in the Three Sisters method, pile up soil in a circular mound, about 2 feet wide and 6 inches tall, and plant three corn plants per mound. Leave 2 to 3 feet of space between the center of each mound to allow room for vining squash to sprawl at their base. Remember that corn is wind pollinated so if you are growing only a handful of plants you will most likely need to hand-pollinate to get full ears. If your block of corn contains at least 16 plants they should be able to pollinate themselves naturally.

Corn requires a lot of nitrogen to produce a good crop, so you will likely benefit from amending your garden beds with a slow-release fertilizer like manure or feather meal before planting your corn. To reduce the amount of fertilizer needed, you can grow a legume cover crop like beans, peas, or clover in the spring and then mow them down or work them into the soil before you plant your corn. If you are using the Three Sisters method, the beans provide some nitrogen while they grow together with the corn.

Pests and Disease

The primary insect pests that will attack corn in most of the U.S. are European Corn Borers and Corn Ear Worms. These moths lay their eggs on the corn and their larvae tunnel through the stalk or eat the fresh kernels of corn as they develop. Often the damage is not too severe and you can simply cut off the damaged ends of the ears. The moths typically overwinter in corn stalk residue so one very effective management strategy is to remove the stalks from your previous year’s garden and compost or burn them to keep the population in check.

Cutworms can also be a problem for newly emerging corn seedlings. If you ever arrive at your corn patch to discover that a number of the seedlings appear to be cut at the base and are laying on their side, you are likely dealing with cutworms (or a rival gardener). In a small patch you can manage these by scanning the ground and physically removing the caterpillars, but if the problem is larger you may want to apply a treatment of the organic pesticide Spinosad.

Chipmunks and other small rodents will sometimes dig up newly planted corn seeds for a little snack, so you’ll enter your garden to find a series of freshly dug holes where your corn seeds were once buried. To avoid this, you can either cover your corn patch with bird netting until the plants are about 2 inches tall or start your corn in seedling trays and transplant them into the garden.

The most common disease that impacts corn in the Americas is a fungus referred to as “Corn Smut” in the U.S. and “Huitlacoche” in Mexico. Though referring to it as a disease is actually a matter of perspective because it is considered a delicacy in parts of Mexico. Many people intentionally infect their corn fields in order to grow this delicious fungus. On our homestead, we would be disappointed if our whole field was infected, but we don’t mind finding a few ears exploding with the bulbous fungus.

Harvest and Use

If you are growing a sweet corn variety you’ll want to time your harvest carefully in order to maximize the sugar content. Generally, sweet corn should be ready to harvest when the silks emerging from the end of the ear begin to turn brown. You can also peel back the husk to reveal the kernels and pop a few with your fingernail. If they are nice and full and a white liquid bursts out when they are popped, it’s ready to harvest.

For flint, flour, and dent corn you can simply allow them to hang on the plant until they are dry. Be careful not to leave them for too long though because we aren’t the only animals who love to eat corn. We like to allow our ears to mature completely and then pick them as soon as the husks turn brown and dry. They can then be hung indoors to continue drying. Once dry, corn will store indefinitely and you can use it as needed to fill your belly throughout the winter and spring.

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