Nothing says summer like a freshly grilled ear of corn on the cob, and the best way to get the most flavorful corn is to grow it yourself. The sugars in corn start turning to starches almost the moment it's harvested, so to get peak flavor, corn is best eaten the day it's harvested. Luckily, learning how to grow corn is easy if you have enough space and keep a few important things in mind.
When to Plant Corn
Corn cannot handle frost, so it shouldn't be planted out until after danger of frost in your hardiness zone, and once the soil has warmed a bit. Cold soil will result in your corn seed rotting rather than sprouting. If it's after your last frost date but the soil still feels cold, either wait a few more days or place black plastic over the soil to help it warm up more quickly before planting corn.
- Corn generally dislikes having its roots disturbed, so direct-sowing is the way to go.
- However, if you live in a short-season zone and want to get a jump on the season, you can sow it indoors under lights. Your best bet here is to use peat pots, pellets, or soil blocks so you don't have to disturb the roots when planting.
- If you want to be able to harvest regularly, sowing a new crop every two weeks through early summer will ensure you have a steady supply in late summer and early fall.
How to Grow Corn
Plant corn two inches deep and twelve inches apart. You can sow more thickly if you're concerned about birds or squirrels snatching the seeds before they germinate, but you'll have to thin them later to be no closer than a foot apart. Corn needs to pollinate itself in order to produce ears, so planting in blocks no smaller than three feet by three feet is preferable to planting in rows.
- Plant in fertile, well-drained soil in full sun.
- The area should be completely free of weeds, rocks, and other debris, since corn roots are quite shallow and can't compete well with other objects until the plants are established.
- Keep the bed evenly moist and continue weeding.
- Once the plants are up, keep them well watered and weeded.
- It's a good idea to mulch around the plants, both to conserve water and reduce weeds.
- Keeping the soil evenly moist is important - corn is very shallow-rooted, so if the soil dries out or weeds start to take over, it can result in weak growth for the corn plants.
Another tried-and-true method for ensuring the roots stay moist is to make furrows in your garden bed a few inches deep, mounding the soil on either side of each furrow. Plant the seed at the bottom of the furrow. Any rain or irrigation water will collect in the furrows, providing moisture where the plants need it most.
Feed Your Corn Plants
Corn is a heavy feeder, and, as mentioned above, requires steady, regular watering. Side-dress your corn plants with compost or composted manure once per month during the growing season. It's also beneficial to feed them at certain points during their growth cycle.
- When the plants are about eight inches tall
- When the plants reach knee-height
- When tassels start forming
- And again when ears start developing
Feed with balanced organic fertilizer, compost tea, fish emulsion, or kelp meal. If, at any point during ear production, the foliage of your corn plants starts turning from deep green to a light, yellowy green, it means they need more fertilization. Feel free to give them another dose of fertilizer and a good, deep watering.
When tassels and silks form, that's when the plants are working on pollination. To help them along, give your plants a gentle shake every couple of days to encourage the pollen from the top of the plant to fall onto the tassels.
Harvesting corn at its peak is essential for the best flavor.
Watch the Silks
Keep an eye on the silks (at the ends of each ear of corn) for a hint about when your corn is ready to harvest. Once they turn from yellowish-white to dark brown, it's likely that the corn is ready.
Check the Kernels
To make absolutely sure that the corn is at peak sweetness and ripeness, peel a bit of the husk back and gently pierce one of the kernels with your thumb nail. Milky sap should drip from the pierced kernel. It should look a lot like skim milk, sort of watery white. If it's clear, the corn isn't ripe yet. Let it go a few more days and try again.
Harvest the Ears
The easiest way to harvest corn is to hold on to the stalk with one hand and grasp the ear of corn with the other. Gently pull and give a bit of a twist, and the ear of corn should come off easily.
Select the Best Corn Variety
When purchasing seed for corn, there are generally three types of corn available:
- Standard: These include many heirloom and old-fashioned varieties, and are often marked with the abbreviation SU in seed catalogs.
- Sugar-enhanced: These varieties are denoted with an SE abbreviation, are bred to have additional sweetness, and they retain that sweetness longer after harvesting.
- Supersweet: Also referred to as "shrunken" varieties due to the wrinkly, shrunken appearance of the dried seed kernels, these are bred to have high amounts of sugar, though the plants may not be as vigorous or grow as many ears as other varieties. Look for the SH2 abbreviation in seed catalogs and on seed packets that denote supersweet varieties.
Planting Considerations Based on Variety
Once you know what level of sweetness you're looking for, the next thing to consider is the length of your growing season. Corn generally takes a long time to produce a harvestable crop - anywhere from 90 to 120 days from planting to harvest, depending on variety.
If you live in an area with a shorter growing season, look for varieties that take around 90 days to harvest, and that will give you time to sow one or two succession plantings if you'd like, with plenty of time for your corn to mature.
Corn Pests and Diseases
Aside from the fact that corn can be a bit picky about water, it also comes with its fair share of pests, of the four-legged, winged, and insect varieties.
Deer and Other Mammals
Deer and raccoons both love corn. Rabbits will mow small corn plants down to the ground. The best way to protect your corn from the four-legged variety of pests is to either enclose the area in a tall fence or drape bird netting over the entire area. This will make it difficult for animals to munch on your plants.
A flock of hungry birds can decimate a plot of ripening corn in a matter of hours.
- Bird netting placed over your plot (as long as your plot is small enough) is the best way to protect it.
- If you have a bigger area, the Cornell Cooperative Extension Service tested a variety of methods and found that the use of helium balloons with large eye-shaped designs painted on them seemed to deter birds, as did the large "dancing" type of blow up figures (the kind one often sees outside of car dealerships or other stores).
The key with both of these somewhat oddball methods is that they have to be in place before the birds find your corn, so they're never tempted to consider stopping in the first place.
Corn Insect Pests
Insects can also do significant damage to corn crops.
- Cucumber beetle larvae sometimes burrow into the roots of corn plants and feed on them, which weakens the plant. If you spot them, treating the soil in your corn patch with Heterorhabditis nematodes, which will kill the larvae.
- Flea beetles often chew small, round holes in the foliage of leaves. They're often more of a problem during the seedling phase and are less of an issue for mature plants. If you notice either the tiny beetles or the chew holes they leave in your plants, consider installing sticky traps that will capture them as they jump from plant to plant, or spray your plants with insecticidal soap.
- Cutworms can be an issue during the early seedling phase. They eat right through the stems of young plants, making them fall over like tiny trees that have been chopped down. If you notice this type of damage in your garden, the easiest way to prevent further damage is to surround each of the plants in the area with a homemade cutworm "collar," which is essentially a strip of cardboard or plastic formed into a circle and pushed into the soil around the plant so that it sticks up a couple inches above the soil. This prevents cutworms from accessing your plants and damaging them. Once the stem is about as thick as a pencil, remove the cutworm collar.
- Corn earworm larvae hatch on the silks of the corn plants and then burrow into the newly forming ears, feeding on them. If you notice these larvae on your plants, hand-pick them or dust the silks with Bt (bacillus thuringiensis) which will kill them. Or, if you've had this issue before, you can try securing the tassel end of each ear closed with a wooden clothespin to prevent the larvae from getting into the ears, though this is rather time-intensive if you're growing a lot of corn.
- Grasshoppers can be voracious and destructive, chewing their way through young corn foliage in no time. An easy way to deter them is to boil several cloves of garlic in some water and let it cool. Strain out the garlic and then spray the garlic tea all over your corn plants. Grasshoppers will steer clear of your plants, but you may have to apply it a few times, especially if it rains.
There aren't really many diseases that affect corn plants, but one to keep an eye out for is corn smut. Corn smut creates pale, swollen areas along the ears of corn, and when they burst, they release a black, powdery fungus that can stay in the soil for up to seven years, putting any future corn harvests at risk for infection. If you spot the round, pale galls on the ears of corn, pull them off immediately and discard them -- not in your compost pile -- to prevent the smut from spreading.
Tips for Growing Corn
Growing corn takes some time and attention, but it's absolutely worth it. As long as you keep a few things in mind, you'll be well on your way to a corn harvest of your own:
- Plant after all danger of frost.
- Keep the area weed free and catch any pest problems early.
- Water regularly and evenly, and mulch to conserve moisture.
- Feed corn regularly for optimum growth.
Enjoy Home Grown Corn
With the above tips, you're sure to enjoy some sweet, home-grown corn. While it takes a little time from seed to harvest, having summer corn on the table makes the effort worth it.