The Vegetable Garden

Corn - When To Plant

    When To Plant

    Sweet corn requires warm soil for germination (above 55°F for standard sweet corn varieties and about 65°F for supersweet varieties). Early plantings of standard sweet corn should be made at, or just before, the mean frost-free date unless you use special soil-warming protection such as clear polyethylene mulch film.

    For a continuous supply of sweet corn throughout the summer, plant an early variety, a second early variety and a main-crop variety in the first planting. For example, you may wish to select Sundance (69 days) for the first early variety, Tuxedo (75 days) for the second early variety and Incredible (83 days) for the main-crop variety. Make a second planting and successive plantings of your favorite main-crop or late variety when three to four leaves have appeared on the seedlings in the previous planting. Plantings can be made as late as the first week of July.

    Spacing & Depth

    Plant the kernels (seeds) 1/2 inch deep in cool, moist soils and 1 to 1 1/2 inches deep in warm, dry soils. Space the kernels 9 to 12 inches apart in the row. Plant two or more rows of each variety side by side to ensure good pollination and ear development. Allow 30 to 36 inches between rows.

    All sweet corns should be protected from possible cross-pollination by other types of corn (field, pop or flint). If you plant supersweet or synergistic sweet corn varieties, plan your garden arrangement and planting schedule so as to prevent cross-pollination between these varieties and with any other corn, including nonSh2 sweet corns. Supersweet varieties pollinated by standard sweet corn, popcorn or field corn do not develop a high sugar content and are starchy. Cross-pollination between yellow and white sweet corn varieties of the same type affects only the appearance of the white corn, not the eating quality.

    Care

    Cultivate shallowly to control weeds. Chemical herbicides are not recommended for home gardens. Although corn is a warm-weather crop, lack of water at critical periods can seriously reduce quality and yield. If rainfall is deficient, irrigate thoroughly during emergence of the tassels, silking and maturation of the ears.

    Hot, drought conditions during pollination result in missing kernels, small ears and poor development of the tips of the ears. Side-dress nitrogen fertilizer when the plants are 12 to 18 inches tall.

    Some sweet corn varieties produce more side shoots or "suckers" than others. Removing these side shoots is time consuming and does not improve yields.