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Sweet Corn Growing Tips

Corn ears1

Grow corn in the warm time of the year. Direct sow corn after all danger of frost has passed. Make succession sowings for a continuous harvest throughout the growing season.

Three types of sweet corn

Corn growing starts with deciding which type of corn to plant: standard, sugar-enhanced, or super-sweet.

  • Standard sweet corn varieties (sometimes called “normal sugar”) have old-time “corny” flavor. ‘Golden Bantam’ is a classic yellow-kernel standard sweet corn, also ‘Country Gentleman’ (white kernels), ‘Silver Queen’ (white) and ‘Double Standard’ and ‘Honey and Cream’ (both bi-color kernels).
  • Sugar-enhanced corn cultivars are sweeter and tenderer than standard varieties. ‘Bodacious’, ‘Early Choice’, and ‘Kandy Korn’ are yellow kernel sugar-enhanced cultivars. ‘Platinum Lady’ and ‘Alpine’ have white kernels. ‘Gold ‘N Pearl’. ‘D’Artagnan’, and ‘Peaches and Cream’ are sugar-enhanced bi-colors.
  • Super-sweet corn cultivars are the sweetest of all but can lack flavor and tenderness. Yellow kernel super-sweet cultivars include ‘Illini Xtra-Sweet’ and ‘Krispy King.’ ‘How Sweet It Is’, ‘Sugarburst’, and ‘Aspen’ are white kernelled. ‘Honey ‘N Pearl’ and ‘Skyline’ are bicolor.
Corn seedling grow plant
Corn seedlings

Planting corn

Temperature. Sow or plant corn directly in the garden two weeks after all danger of frost is past and the soil has warmed to 60°F. In cool regions and where cool weather persists, spread black plastic on the planting area to speed ground warming, or sow seed in sun-warmed ridges about 3 inches above the planting bed. Protect young seedlings from chilly nights with a floating row cover.

Indoor Seed Starting Corn. Corn can be started indoors in peat pots to avoid disturbing the roots at transplanting time. Seeds germinate at 50°F. Seedlings should go into the garden within a couple of weeks of emergence; this is important to avoid a check in growth. Time indoor sowing so that corn goes into the garden when the outdoor temperatures are very warm; corn loves heat.

Sowing Corn Outdoors. Early in the season, sow corn seeds 1 inch deep; after the weather has grown hot in mid-summer, sow corn 3 to 4 inches deep. Set seed 2 to 3 inches apart in rows; space rows 30 to 36 inches apart. (Closer spacing will result in smaller ears at harvest.) Make successive sowings every 2 to 3 weeks for a continuous harvest summer into fall or plant early, midseason, and late varieties at the same time.

Corn care through the season

Thinning Corn. Thin corn seedlings 10 to 14 inches apart. Thin unwanted seedlings by cutting them off at soil level; don’t pull up unwanted seedlings, you may disturb the roots of plants nearby.

Feeding Corn. Corn is a heavy feeder. Place a band of aged compost in a furrow two inches from where you are going to sow the seed and an inch deeper than seed level. Feed corn with a high-nitrogen fertilizer or side-dress with aged compost when stalks are 8 inches high and again when they are 18 to 24 inches high. Corn will grow particularly well where nitrogen-setting beans and legumes have grown the season before. The winter before planting corn, add aged manure and compost into the planting bed and work it into the soil with a garden fork.

Weeding. Corn is shallow rooted; competing weeds can rob corn of nutrients and moisture. Keep weeds out of the corn patch especially during the first month of growth. After that, control weeds by applying thick mulch of compost. A cover crop of nitrogen-setting clover planted a month after corn is planted will also keep weeds down.

Corn pollination

Corn is wind-pollinated (and easily cross-pollinates). Planting corn in short blocks of 3 to 4 rows rather than a single row will aid wind pollination and increase yield. To avoid cross-pollination, plant different corn varieties at least 100 or more feet apart or plant so they tassel two weeks apart. (A corn stalk is topped by a flowering tassel that produces pollen. The wind carries the pollen to silky threads on the ears a quarter the way down the stalk. Each silk is connected to an unfertilized kernel. The number of kernels in an ear is the same as the number of silks that were pollinated.)

Lodging corn

If maturing corn stalks begin to fall over (called “lodging”), simply straighten them up and pack some soil around the roots and crown of the plant. Hilling corn early in the season may prevent lodging: use a hoe to draw up soil around the stalks as they mature.

Corn grow plant harvest
Corn near harvest

Corn harvest

Harvest is near when ears are plump and silks have withered, about three weeks after the silks appear. To know when to pick corn–apart from ears being plump, pull back part of the husk and pierce a kernel with your thumbnail. If there a milky juice spurts out, the sweet corn is ripe. (If the juice is watery, the corn is immature. If the juice is pasty, the corn is past its prime.) Corn is at the peak of sweetness for two to five days.

Corn Yield. Corn will yield 1 to 2 ears per plant, about 10 to 12 ears per 10-foot row. Plant 10 to 15 plants per person.

More tips at How to Grow Corn.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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