A highly anticipated part of summer each year, sweet corn is treasured for its crisp, juicy kernels. To achieve full ears of sweet corn kernels, gardeners must provide specific growing conditions for their sweet corn. Planting space, watering, fertilization and growing corn in thick blocks rather than long, skinny rows are important for producing optimum yields of ear corn.
Once sprouted, corn has a remarkable ability to tolerate light frosts because its growing tip is protected by several outer layers of existing leaves. Seed, though, fares poorly in soils that are overly cold and damp and will rot quickly if planted too early in the growing season. Corn seed should be planted no more than an inch deep once temperatures are consistently above 55 degrees F at night.
After germination, corn grows very rapidly, earning its reputation for being fertilizer dependent to grow to its full potential. Corn is often referred to as one of the "heavy feeder" species in the garden, and as such, should be fertilized with a nitrogen-rich vegetable fertilizer once it reaches 4 inches. A second application is recommended once plants reach 10 inches. Ears generally reach ripeness between 60 and 90 days, depending on the variety.
Tasseling and Silk Emergence
Corn is a self-pollinating plant. Male pollen particles are produced on tassels at the top of the plant, while the female silks emerge at one or two leaf junctures roughly midway up the stalk. Because wind is the primary agent of pollination, corn should be planted in blocks of three to four rows each to ensure thorough pollination. In smaller gardens, corn can be easily hand-pollinated either by shaking the male tassels after the silks emerge, or by cutting the tassels and shaking them directly over the silks after emergence.
Each kernel on a ripe ear of corn is represented by a single strand of silk. Silks are pollinated when one grain of pollen adheres to the silk, which triggers the kernel ripening process. Often, ripe ears of corn have fewer kernels at the tip than in the middle or at the base; this is because silks corresponding with lower kernels are usually among the first to be fertilized. Ears are usually at their peak ripeness at between 15 and 20 days after pollination.
Planting corn in blocks is the easiest solution for ensuring thorough pollination; interplanting several types of corn will lead to cross-pollination. Cross-pollination of sweet corn varieties with popcorn or other types can lead to starchy, chewy kernels. Planting two to five "barrier" rows can help reduce cross-pollination between neighboring stands of differing varieties of corn.