How to Grow Sweet Corn: The Complete Guide

The most common reasons for slow growth include poor light levels, not enough moisture, or a lack of nutrients. Plant in full sun (at least 6 to 8 hours of direct sunlight). Soil needs to be consistently moist (though well-draining),as corn tends to suck up a lot of water. Corn is a hungry plant, so it’s important to enrich beds with lots of organic matter, such as garden compost (ideally in the fall).

When to Plant Corn

• Most gardeners sow corn directly in the garden soil (versus indoors) so that their sensitive roots aren’t disturbed when transplanting.
• Corn is very sensitive to frost; do not plant soil temperature is at least 60°F (16°C), or 65°F (18°C) for super-sweet varieties. Usually, this is 2 or 3 weeks after the last frost in spring. See our Planting Calendar for corn based on average frost dates.
  • If you live in an area with a shorter growing season, choose an early variety that will mature well before the first fall frost. The ground can be warmed by a black plastic cover; sow seeds through holes in the plastic.
• A couple of weeks after planting your first round of corn, plant another round in order to extend the harvest.

How to Plant Corn

• To speed germination, moisten seeds, wrap them in moist paper towels, and store them in a plastic bag for 24 hours.
• Because corn is wind-pollinated, it’s essential to plant in a block, rather than a single row. For decent pollination, we recommend a modest block of, say, 10 to 50 plants. This maximizes the chances of the pollen released from the male tassels at the top of the plants drifting down into contact with the female silks lower down. Incomplete or inconsistent kernel development, with the cobs only partly or sporadically filled, is down to poor pollination. The silks protruding from the end of each cob are responsible for carrying the pollen down to the kernels. One strand connects to one kernel, so for complete fill, every strand of the silk must be pollinated.
• Sow seeds about 1½ to 2 inches deep and 12 inches apart in rows 2½ to 3 feet apart. Don’t plant too close together or you run the risk of disappointingly small cobs.
• You may choose to fertilize at planting time with a general purpose (10-10-10 fertilizer); corn is meant to grow rapidly.
• Water well at planting time.

Sowing Corn Indoors

If you’re going to start seeds early, sow the seeds in pots under the protection of a greenhouse, hoop house, or cold frame. This means you can begin sowing three to four weeks before your last frost date, giving you a head start on corn sown outdoors—a huge advantage for areas with shorter growing seasons.

Sow eight to ten seeds half an inch deep into four-inch-wide pots, or sow two seeds per module in a plug tray and remove the weakest of the two seedlings when they emerge. Keep the potting soil moist as they grow on.

Harden off the plants as your recommended planting time approaches by placing them outside for increasingly longer spells over the course of about a week. Plants should be at least six inches tall by the time they’re transplanted outdoors.

Check out this video for great tips on growing juicy corn: