The corn plant’s blooming period represents its reproductive phase, which is the most sensitive time for determining the final yield of the crop. This stage involves the appearance of two separate flower types on the same plant, known as monoecious flowering. Successful fertilization during this window is directly tied to the number of kernels that will develop on each ear. This transition initiates a period that requires close management.
Identifying the Male and Female Flowers
The corn plant distinguishes its male and female flowers by their location and appearance. The male flower, called the tassel, develops at the top of the plant and is the source of pollen. A healthy tassel produces millions of pollen grains, far more than necessary for the number of silks on the plant.
The female flowers are the silks, which emerge from the developing ears lower down on the stalk. Each strand of silk is connected to a single ovule, which will become a kernel if successfully fertilized. Silks are sticky and covered with fine hairs, enabling them to capture airborne pollen grains. The silks emerge progressively, with those at the base appearing first and the tip silks emerging last.
Ensuring Successful Pollination
Corn pollination relies on the wind carrying pollen from the tassels down to the silks, making planting configuration a major factor. Because a single plant’s pollen rarely fertilizes its own silks, corn should be planted in blocks of short rows rather than long, single rows. This block arrangement increases plant density, improving the chance that pollen shed from one plant will land on the silks of a neighboring plant. Approximately 97% of successful pollination comes from pollen shed by other plants.
For small-scale growers, supplemental hand pollination is a practical way to ensure a full kernel set and prevent barren spots. The best time for this intervention is typically in the late morning, after the dew has evaporated but before the hottest part of the day. Pollen viability is greatest when humidity is low and temperatures are moderate.
To hand pollinate, gently shake the fully open tassel over the newly emerged silks to dust them with pollen. An alternative method involves cutting a tassel, shaking the pollen into a small bag, and then lightly brushing the silks of the developing ears with the collected pollen. Since the silks emerge sequentially, repeat the hand pollination process over two to three days to ensure the later-emerging silks at the ear’s tip are also fertilized.
Adjusting Care During the Flowering Phase
The transition to flowering marks the period of peak water demand, making irrigation adjustments necessary. During the silking and pollen shed phases, the plant’s water use can peak, requiring up to 0.33 inches of water per day. Water stress is damaging because it can delay silk emergence and elongation, causing them to miss the brief window of pollen shed.
Heat stress, especially when temperatures exceed 92°F (or 86°F with dry soil), can compromise pollen viability. Maintaining adequate soil moisture through irrigation is the most effective way to mitigate the harmful effects of high temperatures, as the water cools the plant through evaporative processes. Monitoring for signs of heat stress, such as leaf rolling, is important for proactively adjusting watering schedules.
Nutrient management focuses on supplying adequate nitrogen and phosphorus during this reproductive stage. Nitrogen supports the high metabolic rate of flowering and grain fill, while phosphorus is involved in energy transfer within the developing kernels. Ensuring a continuous supply of these nutrients and water is paramount to supporting the plant through this high-demand phase.
Monitoring Kernel Development
Once pollination has successfully occurred, the silks connected to the fertilized ovules begin to detach, dry out, and turn brown. This browning of the silks is the first visual confirmation that fertilization has taken place, typically occurring within two days of the pollen landing. Silks that remain green and attached indicate ovules that were not fertilized, resulting in missing kernels on that part of the ear.
The fertilized ovules then enter the initial stages of kernel development, progressing through several phases:
- Blister stage: Approximately 10 to 14 days after silking, kernels contain a clear, watery fluid.
- Milk stage: Around 18 to 22 days after silking, the fluid inside turns milky white due to starch accumulation.
- Dough stage: The inner material thickens to a dough-like consistency.
Monitoring these stages allows the grower to estimate the time until harvest. The crop moves toward the dent stage, where the kernel crowns begin to dry and show a small indentation. The final stage is physiological maturity, or the black layer stage, which occurs when a distinct black line forms where the kernel attaches to the cob, signifying that no more nutrients will be deposited into the kernel.