Seed saving involves collecting mature seeds from plants to cultivate a new generation, fostering self-sufficiency and maintaining unique varietal characteristics. Corn (Zea mays) is rewarding for this process, producing large seeds that are easy to handle and store. Unlike many garden vegetables, corn is wind-pollinated, meaning pollen can travel significant distances. Preventing unwanted cross-pollination is a primary consideration to ensure saved seeds grow true to the parent plant.
Selecting the Right Corn for Seed Saving
The decision to save corn seed must begin with the variety selected for planting, as not all corn is suitable for successful seed saving. Gardeners must choose an open-pollinated (OP) variety, which includes heirloom types, because their genetic makeup is stable, meaning the offspring will closely resemble the parent plant. Hybrid varieties, often labeled as F1, are the first-generation cross of two distinct parent lines, and saving seed from them is unreliable, as the resulting plants will show unpredictable traits in the next season.
Managing cross-pollination is the most important step for saving pure corn seed. Since corn is wind-pollinated, pollen can travel hundreds of feet, making physical isolation necessary. A common technique is to plant the chosen variety at a significant distance, ideally 600 to 1,000 feet away from any other corn varieties, including neighbors’ sweet or field corn.
If space constraints make isolation by distance impossible, gardeners can employ isolation by time. This method involves staggering the planting dates of different corn varieties so that their pollination windows do not overlap. A difference of about three to four weeks between the silking and tasseling stages of two varieties is generally sufficient to prevent genetic mixing. Furthermore, selecting the best-performing plants with desirable traits, such as strong stalks and well-filled ears, is necessary to maintain the vigor and genetic diversity of the seed stock over time.
Harvesting and Curing the Cob
The timing of the harvest for seed corn is significantly later than for eating, and the ears must be allowed to fully dry on the stalk before picking. The corn is ready for seed collection when the kernels are hard and dry, the husks have turned brown and papery, and the entire stalk is completely dried out. A simple test to confirm maturity is pressing a kernel with a thumbnail; if it does not dent or yield any liquid, the corn has reached the necessary stage of hardness.
After harvest, the ears must undergo “curing” to reduce moisture content for safe storage. This initial drying occurs while kernels are attached to the cob, allowing the cob to draw moisture from them. To facilitate air circulation and prevent mold, the husks should be peeled back or entirely removed.
The cobs are then hung or laid out in a single layer in a sheltered location that is dry, well-ventilated, and protected from rodents and rain. Curing can be achieved by braiding the husks together and hanging them in a barn or garage, or by spreading the ears on a wire rack or screen. This process can take several weeks or even months, depending on the ambient humidity, and it is necessary to bring the seed moisture down before the kernels are removed from the cob.
Processing and Storing the Seeds
After curing, the kernels must be shelled before long-term storage. For small batches, shelling can be done manually or with a small hand-held corn sheller. It is common practice to discard the small, irregularly shaped kernels from the tips and bases, saving only the larger, well-formed kernels from the middle section.
Before storage, the kernels must be tested for sufficient dryness, as any remaining moisture can lead to mold or a loss of viability. The ideal moisture content for corn seed storage is approximately 10 to 12 percent. A practical method to check for this level of dryness is the “shatter test,” where a kernel is placed on a hard surface and struck with a hammer; a fully dry kernel will shatter, while a moist one will flatten or crush.
Once adequately dry, seeds should be stored in an airtight container, such as a glass jar, to prevent reabsorbing moisture. Storing them in a cool, dark location, like a refrigerator or root cellar, preserves viability. Adding a small desiccant packet, such as silica gel or dry rice, provides extra protection against humidity fluctuations.