Generally corn seed has an average useful life of two years, according to the University of Washington Extension. As seed ages beyond two years, its germination rate continues to decrease so that generally the older the seed, the fewer kernels you can expect to grow. But whether old corn seed will sprout also depends on how it has been stored. And even with the best seed, appropriate temperature and moisture are needed to encourage germination. Proper indoor and outdoor sprouting techniques should achieve similar results.
Sprouting Corn Indoors
Soak seeds overnight in water. Maintain water and room temperature between 65 and 75 degrees.
Place soaked seeds on top of a damp paper towel. Place the paper towel with seeds into a resealable plastic bag and seal. Set the sealed bag in a warm place (about 65 to 75 degrees) out of direct sunlight.
Keep the bag at room temperature for about a week to ten days. Check the seeds every few days for signs of sprouting and to make sure the paper towel remains moist. Plant sprouted seeds one inch deep and eight to 12 inches apart in garden rows. Discard non-sprouting seeds if they begin rotting, or after about two weeks.
Sprouting Corn Outdoors
Soak seeds in water overnight. Both room and water temperature should be between 65 and 75 degrees.
Plant seeds outdoors when danger of frost is passed, in soil that is at least 65 degrees. Plant four to five seeds close together in a row, each seed about three inches apart. Then leave about 20 inches of row space before repeating with about five more seeds, each three inches apart. By clustering seeds in this way you may compensate for the non-germinating seeds.
Water seeds after planting and water weekly so the seedlings receive about an inch of water per week, including rain water.
After germination and leaf emergence, thin corn plants if needed, or reseed in areas where few seeds have germinated. Continue watering corn plants weekly.
About this Author
Ann Wolters, who has been a freelance writer, consultant, and writing coach for the past year and a half, has had her writing published in "The Saint Paul Almanac," and in magazines such as "Inventing Tomorrow" and "Frontiers." She earned a master’s degree in English as a second language from the University of Minnesota and taught English as a foreign language for nearly seven years.