Corn is a wind-pollinated crop, relying on air currents to carry pollen from male flowers to female flowers. When growing corn in small plots or blocks, natural wind pollination is often inefficient for producing full ears. Manual pollination becomes necessary to overcome issues like poor air circulation or limited plant numbers. Hand pollination helps guarantee that nearly every potential kernel receives the required pollen, leading to a better yield of fully formed ears.
Identifying Male and Female Flowers and Optimal Timing
The corn plant produces two distinct flower types: the male tassel and the female silk. The tassel is the branched structure located at the very top of the stalk, and it releases the yellow, dust-like pollen. The silks are the fine, hair-like strands that emerge from the developing ears lower down on the stalk. Each silk strand connects to a single ovule that will become a kernel. Successful pollination requires synchrony, meaning the pollen must be shedding from the tassel at the same time the silks are receptive.
A silk is ready to receive pollen when it is moist and slightly sticky to the touch. Pollen shed typically occurs over a period of five to eight days, and silks remain receptive for up to ten days. The first four to five days are when most successful fertilization occurs. The best time of day to perform the hand-pollination is generally in the mid-morning, between 8:00 a.m. and 11:00 a.m., after the morning dew has dried and before high temperatures reduce pollen viability.
Step-by-Step Guide to Collecting and Applying Pollen
The first action is collecting the pollen from the mature tassels, which should be done when the anthers are open and visibly shedding the yellow dust. A common collection method is to gently bend the tassel over a clean, dry paper bag, bucket, or small container. Shaking the tassel lightly will dislodge the pollen grains into the container, ensuring a concentrated supply. Collecting pollen from several different tassels helps ensure genetic diversity and maximizes the amount available for application.
Once collected, the pollen needs to be applied to the receptive silks, which should be slightly sticky and light in color. One precise method for application is using a small, soft-bristled paintbrush or a cotton swab, which can be dipped into the collected pollen. The pollen-dusted brush is then gently swept across the entire surface of the exposed silks on the developing ear. The goal is to dust the pollen evenly over every silk strand, as each strand represents one potential kernel.
An alternative method, especially useful for multiple ears, involves using the paper bag containing the collected pollen. The bag is placed over the exposed silks of an ear, and the contents are gently shaken or poured directly over the silks. This technique mimics the wind-driven dispersal of a natural setting, aiming to coat the silks thoroughly with a fine layer of pollen.
Tips for Maximizing Pollination Success
To ensure a full ear of corn, the hand-pollination process should be repeated over several days. Silks emerge sequentially, starting from the base of the ear and progressing toward the tip. Repeating the application for three to five consecutive days ensures that all newly emerged silks are coated with fresh, viable pollen.
Environmental conditions play a role in success, so it is best to avoid manual pollination during periods of heavy rain or high winds. Moisture on the tassel can prevent the pollen from being released, and high humidity or high temperatures above 90°F can quickly reduce pollen viability. After the process is complete, successful pollination can be verified by observing the silks approximately two days later.
To check for success, gently peel back the husk and lightly shake the ear; if the silks fall away, fertilization has occurred. If silks remain firmly attached, it indicates that the corresponding ovules have not been fertilized, which would result in missing kernels or “skips” on the mature cob. Unpollinated silks may also continue to grow, resulting in unusually long strands, while fertilized silks will stop elongating.