How to Grow Sweet Corn

Shucking and ear of corn

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Corn is one of the most popular vegetables to grow and eat, and it's all the more delicious when freshly harvested. It's also surprisingly easy to grow in the home garden. Corn grows from tall, straight stalks that produce husked ears of tender kernels tufted with silks. Most corn varieties look alike on the outside. But under the husks, sweet corn can be white, yellow, red, or even bicolor. Many modern sweet corn varieties have been bred to mature early in the season, but later-maturing types tend to be sweeter.

Sweet corn is a fast-growing annual that is planted in spring and grows through the summer. It is ready to harvest about three months after planting, but early varieties can be ready in as little as two months.

Common Name Sweet corn
Botanical Name Zea mays
Family Poaceae
Plant Type Annual
Size 6–8 ft. tall, 1–2 ft. wide
Sun Exposure Full sun
Soil Type Loamy, well-drained
Soil pH Acidic, neutral (6 to 7)
Bloom Time Summer
Hardiness Zones 2–11 (USDA)
Native Area Mexico

How to Plant Sweet Corn

When to Plant

Plant sweet corn in the spring after all danger of frost has passed. The soil temperature should be at least 60 degrees Fahrenheit. Starting seeds indoors is not recommended, as the seedlings don’t take well to transplanting. 

Selecting a Planting Site

The ideal planting site should have rich, well-draining soil and lots of sun. Container growth is also an option for the smaller varieties. Because corn grows fairly tall, make sure not to plant it near other shorter crops that it might shade out.

Spacing, Depth, and Support

Plant the seeds about an inch deep with a spacing of 4 to 6 inches. Rows should be roughly 3 feet apart. Corn typically can grow without a support structure, as long as you plant it in a spot that’s fairly sheltered from strong winds.

Sweet Corn Plant Care

Light

To grow well and have the ears fill out, corn needs a spot that gets full sun. That means at least six hours of direct sunlight on most days.

Soil

The soil should be loose and loamy with a slightly acidic to neutral soil pH. Heavy soils can inhibit corn's long taproot. The shallow roots that form on the soil surface are predominantly there to anchor the tall plants.

Water

Water regularly, especially if you notice the leaves curling and when the cobs begin to swell. Around an inch of water per week should suffice. And it is ideal to water deeply once a week, rather than provide a little water daily. Also, keep the area free of weeds that will compete for food and water.

Temperature and Humidity

Sweet corn prefers temperatures between 60 and 80 degrees Fahrenheit. It won’t germinate in cold soil. In cold climates, you can cover the soil with black plastic to help it warm quickly in the spring prior to planting. Humidity typically isn’t an issue as long as adequate soil moisture is maintained.

Fertilizer

Corn is a heavy feeder, requiring rich soil. Nitrogen is especially important for robust growth. An inch or two of compost, rotted manure, or fish emulsion worked into the soil in the fall prior to planting is good to feed your corn. Apply a nitrogen fertilizer once the plants are about 8 inches tall and again when they start producing tassels, following label instructions.

Pollination

Because corn is pollinated by the wind, it does best when planted in blocks rather than rows. Pollen from the male tassels needs to make contact with the female silks, and close planting means more contact. Wind pollination also results in easy cross-pollination. So keep different types of corn separated by at least 25 feet, or plant varieties that mature at different times.

closeup of an ear of corn
The Spruce / Autumn Wood 
ears of corn growing
The Spruce / Autumn Wood  
corn field
The Spruce / Autumn Wood 

Types of Sweet Corn

There are hundreds of corn varieties, virtually all falling under six major categories: sweet corn, popcorn, corn for animal feed, dwarf corn, decorative corn, and multicolored Indian corn. Some of the most popular cultivars for growing sweet corn include:

  • 'Early Sunglow': This early producer is good for climates with short growing seasons.
  • 'Silver Queen': This is another early producer with pale white kernels, and it's highly disease-resistant.
  • 'Golden Bantam': This is an heirloom variety often called the original sweet corn.
  • 'Tuxedo': This is a "supersweet" variety with extra-long ears.

Sweet Corn vs. Popcorn

Sweet corn and popcorn varieties may look similar at first glance. But they have some key differences that dictate how they’re eaten. Sweet corn is harvested at peak tenderness when its kernels are juicy and sweet. Popcorn is harvested once the kernels dry out. The kernels are starchier than sweet corn kernels, and they have a harder shell, which allows them to temporarily hold up to the pressure as the interior swells and pops while cooking. 

Harvesting Sweet Corn

Each stalk of sweet corn should produce at least one ear of corn. Pick corn when you see fat, dark green ears with brown tassels. Squeeze to test for firmness and a rounded, not pointed, tip. Finally, pierce a kernel with a fingernail. If it spurts milky liquid, it is ready.

Pull the ears downward, and twist to take the cob off the stalk. Plan to eat or preserve sweet corn immediately after picking, as the sweetness fades soon after harvesting. You can freeze sweet corn by removing the kernels from the ears and storing them in an airtight container. For best results, blanch the corn and then cool it in ice water prior to freezing. It should keep in the freezer for around six months.

How to Grow Sweet Corn in Pots

If you don’t have the right soil conditions or the garden space for growing corn, try container growth. Pick a short variety that tops out at around 5 to 6 feet tall, as the standard varieties typically don't do well in containers. And just like when growing corn in the ground, plant your containers in a block for pollination. You’ll need at least three rows with three or more plants per row. Using a 5-gallon bucket with drainage holes for each plant should work fine. Water when the top inch of soil dries out, making sure not to allow the containers to become waterlogged.

Pruning

Pruning is not necessary for sweet corn plants.

Propagating Sweet Corn

Sweet corn can be propagated by saving seeds to plant the following season. This is a great way to get more plants from a variety you particularly like, as long as no cross-pollination has occurred. You’ll harvest seeds to save at the end of the growing season. Here’s how:

  1. Cover the ears of corn you plan to save for seed with a shoot bag or paper bag when the first tassel appears. 
  2. Leave each cob on the plant to dry for as long as possible. Remove them once the fall weather turns damp. 
  3. Pull back the husks, and hang the ears upside down in a cool, dry spot to dry completely. 
  4. When they’re dry, remove the seeds from each ear. Keep them in a paper bag in a cool, dry spot for planting the next season.

How to Grow Sweet Corn From Seed

Corn seeds generally need soil that’s at least 60 degrees Fahrenheit to germinate. But some varieties need soil that’s at least 65 degrees Fahrenheit, so be sure to check what your variety prefers. Keep the soil evenly moist but not soggy as the seeds germinate. Germination should occur in about seven to 10 days. When seedlings are around 4 inches tall, thin them to 8 to 12 inches apart.

Potting and Repotting Sweet Corn

A loose, well-draining potting mix is best for corn. Add a high-nitrogen fertilizer at the time of planting, following label instructions. Sweet corn doesn't like its roots disturbed, so it's best to use a pot that will accommodate the plant's mature size. If you want to try starting seeds indoors, use a biodegradable pot that can be planted directly into a bigger container or the ground.

Overwintering

Sweet corn is an annual, so no overwintering is necessary. You can leave the stalks in place to dry out and then cut them down to use for fall decor.

Common Pests and Plant Diseases

Animals including rodents and birds will be the biggest pest problem for sweet corn as the ears ripen. Plants also might become infested with corn borers, which can be kept in check with an organic pesticide and by destroying the stalks at the end of the season. Also, be on the lookout for a grayish-black fungus called smut. Remove and destroy affected plants as soon as possible—ideally before the spores spread.

FAQ
  • Is sweet corn easy to grow?

    Sweet corn is fairly easy to grow as long as you have the space for multiple plants.

  • How long does it take to grow sweet corn?

    Sweet corn varieties generally take between two and three months to mature.

  • Does sweet corn come back every year?

    Sweet corn is an annual, completing its life cycle in one growing season.