Corn, botanically known as Zea mays, is a towering annual grass and one of the world’s most widely cultivated staple crops. Growing corn successfully from saved kernels requires understanding its unique biology and cultural needs. Using kernels harvested from a previous crop is possible, provided the right variety selection and preparation steps are followed.
Selecting and Preparing Kernels for Planting
Selecting open-pollinated or heirloom varieties is recommended because their offspring will reliably resemble the parent plant. Hybrid F1 varieties, while often having desirable traits, will produce unpredictable results if their kernels are replanted. Once chosen, the ears must be thoroughly dried to ensure viability and prevent mold during storage. The kernels should be left on the cob and dried in a well-ventilated area, away from direct sunlight, until they are rock-hard and cannot be dented with a fingernail. After drying, remove the kernels and store them in an airtight container, such as a glass jar, in a cool, dark location until planting season.
Site Preparation and Planting Techniques
Corn requires a location that receives full, direct sunlight for at least eight hours each day. The soil should be fertile and well-draining, ideally tilled to a depth of six to eight inches, with a pH between 6.0 and 6.8. Corn is a heavy feeder, so incorporating organic matter, like well-rotted manure or compost, before planting helps establish a nutrient-rich environment.
Timing the planting is crucial, as corn is sensitive to cold soil and frost. Wait until all danger of frost has passed and the soil temperature consistently measures at least 60°F; 65°F to 85°F is optimal for germination. Because corn is wind-pollinated, it must be planted in short, wide blocks of a minimum of four rows, rather than long single rows, to ensure the pollen reaches the silk. This block formation allows the wind to circulate and distribute pollen effectively. Plant kernels one to two inches deep, spaced eight to ten inches between plants, with rows approximately 24 to 36 inches apart.
Ongoing Care and Assisting Pollination
After the seedlings emerge, consistent moisture and nutrient support are necessary to sustain the plant’s rapid growth. Corn requires approximately one inch of water per week, and irrigation is particularly important during the two-week period leading up to and during the tasseling and silking stages. Because the plants have shallow roots, applying an organic mulch helps conserve soil moisture and suppress weed growth.
Corn has a high demand for nitrogen throughout its vegetative stages. Gardeners should “side-dress” the plants with a nitrogen-rich fertilizer when they are 10 to 18 inches tall and again when the tassels first appear. Sidedressing involves applying the fertilizer several inches away from the base of the stalk, allowing the nutrients to wash into the root zone with watering.
The male flower (tassel) appears at the top of the stalk, and the female flowers (silks) emerge from the developing ears lower down. Each strand of silk must capture a grain of pollen to develop a kernel. If the weather is still, gardeners can assist pollination by gently shaking the stalks mid-morning to release the pollen cloud. For smaller patches, hand-pollination can be performed by collecting pollen from a mature tassel in a paper bag and dusting it directly onto the sticky silks.
Determining Maturity and Harvesting
Determining when to harvest depends entirely on the corn’s intended use—whether for fresh eating or for drying and storage. Sweet corn is ready at the “milk stage,” typically 18 to 23 days after the silks first appear. Indicators include silks turning dark brown and dry, and the ear feeling full and firm when squeezed.
To confirm the milk stage, gently peel back a small section of the husk and puncture a kernel with a thumbnail. A milky white liquid should emerge, indicating peak sugar content. If the liquid is clear, the corn is immature; if it is thick or pasty, the corn is past its prime.
For dry corn varieties, such as popcorn or flour corn, the ears must be allowed to mature completely on the stalk. The entire plant, including the husks, should be dry and papery, and the kernels should be hard enough that a thumbnail cannot puncture them. Harvest the dry ears by snapping them downward and off the stalk, then remove the husks. Store the ears in a dry, well-ventilated area until the kernels are fully cured for shelling and long-term storage.