About 10,000 years ago in what is now southern Mexico, subsistence farmers began experimenting with a bushy wild grain called teosinte. Over generations, they selectively bred for larger and larger starch-filled kernels until they developed the ubiquitous grain we now call corn. Corn has a bad reputation in the United States due to 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 is an excellent staple crop and is consumed daily by hundreds of millions of people around the world. In our house, corn is a regular part of the plate in the form of tortillas, cornbread, oatmeal, pupusas, etc. We devote significant amounts of space in our subsistence gardens to grain corn where it grows alongside its sister beans and squash. If you’re striving to produce more of your own food in North America, this is a borderline necessity in your vegetable garden. Read on to learn everything you need to know to grow a successful corn crop this year!
Types of corn
The fresh sweet corn you eat at summer barbecues is what comes to mind for many Americans when we hear the word “corn,” but it’s just one of many varieties. The four main types of corn are flint, meal, tooth, and sweet.
Flint corn is a dense, hard-shelled variety bred for short northern winters. It is packed with starchy carbs and protein. Maybe you’ve never heard of flint corn before, but you’re probably already familiar because that’s where popcorn comes from. This type of corn is also great for grinding into grits and cornmeal or just tossing it into whole stews and cooking for hours.
Flour corn is a soft-shelled variety bred for drier, warmer conditions in the southwest. It has a nutritional profile similar to that of flint corn. It 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 gives you some hybrid vigor. The nutrient profile is similar to the other two, but it forms massive cobs and produces more calories per acre than any other grain crop on Earth. It’s the strain that many of our chemical companies have tweaked a bit so they can patent its DNA – funny when you think of the 10,000 years of work that went into it. Many old varieties like Wapsi Valley, Bloody Butcher and Hickory King are still available in their original forms.
The last type, sweet corn, is mainly different from the others in that it is picked and eaten unripe. The sugary milky liquid that pops from the kernels of sweet corn is what dries to a starch in other types of corn. As the name suggests, sweet corn is bred to have a very high sugar content and basically nothing else. Nutritionally, it’s not as valuable as other types of corn, but it makes a delicious snack nonetheless.
Depending on the type of corn you’re growing, harvest days vary greatly, but every type of corn likes it hot. Most of the 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, it’s probably not very useful. As a general rule, the ground will usually be warm enough for your corn to germinate successfully around the average last frost date in your growing area. Plant your corn where it can grow in full sun and, depending on the temperature, it needs about an inch of rain or irrigation water per week.
To grow conventional corn blocks, space your plants about 6 to 12 inches apart in rows and 2 to 3 feet between rows. Try to maximize the number of rows to form as many squares as possible, this will help with pollination later in the season. To grow traditional mounds, as used in the Three Sisters method, pile soil into a circular mound, approximately 2 feet wide and 6 inches high, and plant three corn plants per mound. Leave 2 to 3 feet of space between the center of each mound to allow room for the climbing gourds to spread out at their base. Remember that corn is pollinated by the wind, so if you’re only growing a handful of plants, you’ll probably have to hand-pollinate to get full cobs. If your block of corn contains at least 16 plants, they should be able to pollinate themselves naturally.
Corn needs a lot of nitrogen to produce a good crop, so you’ll probably benefit from amending your 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 cover crop of legumes like beans, peas, or clover in the spring, then mow or till them into the ground before planting your corn. If you are using the three sisters method, the beans provide nitrogen as they grow along with the corn.
Pests and diseases
The main insect pests that attack corn in most of the United States are European corn borers and corn earworms. These moths lay their eggs on the corn and their larvae tunnel through the stalk or eat the fresh corn kernels as they develop. Often the damage is not too severe and you can simply cut off the damaged ends of the ears. Moths usually overwinter in corn stalk residue. A very effective management strategy is therefore to remove the stems from your garden from the previous year and compost or burn them to control the population.
Cutworms can also be a problem for young emerging corn plants. If you ever arrive at your corn plot to find that a number of seedlings seem to be cut off at the base and are lying on their side, you’re probably dealing with cutworms (or a rival gardener). In a small patch you can manage them by scanning the ground and physically removing the caterpillars, but if the problem is larger you can apply a treatment of the biological 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 prevent this, you can either cover your corn field with bird netting until the plants are about 2 inches tall, or start your corn in seed trays and transplant them into the garden.
The most common disease affecting corn in the Americas is a fungus called ‘Corn Smut’ in the United States and ‘Huitlacoche’ in Mexico. Although calling it a disease is actually a matter of perspective, as it is considered a delicacy in some parts of Mexico. Many people intentionally infect their cornfields in order to grow this delicious fungus. Back home, we’d be disappointed if our whole field was infected, but we don’t mind finding a few cobs exploding with the bulbous fungus.
Harvest and use
If you are growing a variety of sweet corn, you will want to plan your harvest carefully to maximize the sugar content. Generally, sweet corn should be ready to harvest when the silks emerging from the tip of the cob begin to turn brown. You can also remove the husk to reveal the kernels and pop some with your fingernail. If they are nice and full and a white liquid erupts when popped, they are ready to harvest.
For flint, flour, and dentcorn, you can just hang them on the plant until dry. Be careful, however, not to leave them too long because we are not the only animals that like to eat corn. We like to let our ears fully ripen, then pluck them as soon as the husks turn brown and dry. They can then be hung indoors to continue drying. Once dry, corn will keep indefinitely and you can use it as needed to fill your belly throughout winter and spring.