When you bite into a sweet, buttery ear of corn, you're actually eating seeds. Each kernel of corn contains the potential to grow a new corn plant. "Seed corn" refers to those kernels that are cultivated and set aside to grow new crops of corn. Growing seed corn requires some special considerations, and you will also benefit from knowledge of how corn seeds and germination work.
Each grain of seed corn contains everything a new corn plant needs to start its life. A seed coat encloses a thick nutrient called endosperm. In corn, the endosperm gives the plant its sweet taste. Within the seed, you can find a tiny primitive root and leaf, the latter of which absorbs the nutrients inside the seed once it begins growing. As the leaf elongates and breaks free of the seed, the nutrients in the endosperm sustain it until it reaches the surface of the soil and begins producing sugar from photosynthesis.
Seed production involves sexual reproduction in plants. Without it, viable seed corn will not form. Corn pollination occurs with the help of the wind, not bees and other pollinators used by most vegetable plants. Corn tassels produce pollen that, when passed onto the silk strands that attach to the ear, fertilizes the corn seeds within and produces seeds that contain traits from both parent plants.
Because corn is one of the few vegetable crops that produce separate male and female structures, pollination---and the production of good seed corn---can be a bit trickier than with most vegetable plants. According to the Ohio State University Extension, 97 percent of corn seeds are pollinated by other plants, not by themselves.
Crosspollination means that the seeds and the plants that develop from them include traits of both parent plants. As the University of Minnesota Extension points out, crossing sweet corn and popcorn results in a variety that serves neither purpose well. Because of this, plants being used to produce seed corn should be separated by at least 500 feet from other varieties.
Producing seed corn requires the right conditions to ensure a good pollen shed. According to the Ohio State University Extension, pollen shed begins a few days before the corn silks emerge and continues for about a week. During the middle of this time frame, pollen shed is the highest. Pollen shed even depends on the weather. Corn won't shed pollen in rainy or very dry conditions, and plants drop the most pollen in the late morning, between 9 and 11 a.m. Once all of the plant's needs are met, pollination occurs, and a seed corn forms.