PLANTING, GROWING, AND HARVESTING SWEET CORN
By Catherine Boeckmann
Sweet corn is an annual crop with yellow, white, or bi-colored ears. A long, frost-free growing season is necessary. Here’s how to plant, grow, and harvest corn in your garden.
Sweet corn is wind-pollinated, so it should be planted in blocks, rather than in single rows. Early, mid, and late-season varieties extend the harvest, but be mindful: if you miss the optimal harvest time, the corn’s flavor will go downhill fast, as sugars convert to starch.
WHEN TO PLANT CORN
- Plant seeds outdoors approximately two weeks after the last spring frost date. Consult our Planting Calendar (above) to see suggested planting dates for your region.
- It’s important to get corn planted as soon as possible, since it requires a fairly long growing period with warm weather. If you live in an area with a shorter growing season, choose an early variety that will mature well before the first fall frost.
- Make sure the soil temperature is above 60°F (16°C) for successful germination. (Up to 65°F/18°C for super sweet varieties.) In colder zones, the ground can be warmed by a black plastic cover, if necessary. Plant seeds through holes in the plastic.
- A couple weeks after planting your first round of corn, plant another crop to extend the harvest.
CHOOSING AND PREPARING A PLANTING SITE
- Corn plants are picky about their soil. Work in aged manure or compost the fall before planting and let it overwinter in the soil.
- The soil should be well-draining, but must be able to hold some moisture. Corn tends to use a lot of water.
- For sufficient pollination, plan your plot right. Instead of planting two long rows of corn, plant “blocks” of corn at least four rows deep. This ensures that the corn—which is pollinated by wind—has a greater chance of producing viable ears.
HOW TO PLANT CORN
- Starting corn seeds indoors is not recommended. It’s best to start them directly in the garden so that their roots aren’t disturbed due to transplanting.
- Plant seeds 1.5 to 2 inches deep and 4 to 6 inches apart.
- Rows should be spaced 30 to 36 inches apart.
- You may choose to fertilize at planting time; corn is meant to grow rapidly. If you are confident that the soil is adequate, this can be skipped.
- Water well at planting time.
HOW TO GROW CORN
- When your plants are 3 to 4 inches tall, thin them so they are 8 to 12 inches apart.
- Be careful not to damage the roots when weeding.
- In dry conditions, be sure to keep corn well watered due to its shallow roots. Water at a rate of 5 gallons per sq. yard.
- Mulch helps reduce evaporation.
Corn plants are susceptible to several common garden pests:
Spotted Cucumber Beetles
HOW TO HARVEST CORN
Harvest when tassels begin to turn brown and cobs start to swell. Kernels should be full and milky.
Pull ears downward and twist to take off stalk.
Sweet corn varieties begin to lose their sweetness soon after harvesting, so use them as soon as possible.
Prepare for eating or preserving immediately after picking.
HOW TO STORE CORN
Sweet corn freezes well, especially if removed from ears before freezing. Learn how to properly freeze corn.
Corn kernels can also be harvested for other purposes, like corn-filled therapy packs.
There are three types of sweet corn: Normal, sugar-enhanced, and supersweet. Each one contains a different level of sucrose, changing the flavor and texture of the corn. Sweeter varieties will stay sweeter for longer after harvest.
- ‘Iochief’: midseason, normal-sugar variety. Yellow.
- ‘Silver Queen’: normal sugar-variety. Resistant to some bacterial diseases. White.
- ‘Sweet Sunshine’: supersweet variety, disease resistant, high yield. Yellow.
- ‘Argent’: sugar-enhanced variety, good taste. White.
Corn can be a feast for the eyes, too! Look for these ornamental varieties:
- ‘Glass Gem’: Sporting multi-colored, semi-transparent kernels, this is a favorite for kids.
- ‘Painted Mountain’: Looking for the classic “maize” colors? This variety has a great diversity of natural tones.
WIT & WISDOM
Baby corn is produced from regular corn plants that are harvested early, while the ears are immature. Regular sweet corn, sugar-enhanced sweet corn, and supersweet corn varieties can be used, along with a few varieties that are specific for baby corn.
If your corn shucks harder than usual, prepare for a cold winter.
Corn is one of the Three Sisters; its growing style pairs perfectly with beans and squash. Learn more about companion planting.
Corn is great for eating but also has so many other uses including medicinal. Learn more about corn for natural health.
Learn more fun, witty facts about corn.