All types of corn are pollinated by breezes that blow pollen from the male flowers onto the silk threads that emerge from the top of each ear of corn. This is why it is better for home gardeners to grow corn in a block rather than a long row. Each strand of silk is connected to a separate immature seed and is covered in tiny sticky hairs that collect the pollen. If some silk strands don’t receive pollen, kernels may not form along one side of a cob, or near the top of the cob. (Female part of corn plant in photo at left.)
Male flowers form at the top of the corn plant as an upright spike and lower branches that open out like umbrella spokes. Pollen forms in small yellow ovals (anthers) that release their pollen mid morning after dew has dried from the flowers (between about 9 and 11 am). The centre spike is the first part to release its pollen. Pollen release may only last from 3 to 5 days and the released pollen is only viable for up to 24 hours. (Male flower in photo at left.)
It can help when growing small quantities of sweet corn or popcorn to pollinate it by hand, to ensure that the cobs your plants produce are full of juicy kernels. In nature, silks are rarely pollinated by the same plant.
To ensure good pollination, you need a sheet of A4 paper and a clean, dry, soft paintbrush. Fold the paper in half lengthways and open it out, then fold it in half the opposite way and open it out. This helps the paper to form a shallow well. Or, you can use a small clean shallow tray – something easy to manoeuvre between the plants. Hold the paper under a male flower and gently tap the spike and lower branches of the male flower with the handle of the paint brush. When tassels are ready to be pollinated, plenty of bright yellow pollen will fall onto the paper. Collect some of the pollen on the hairs of the paintbrush and dab it onto all sides and the centre of silk strands of other corn plants. Repeat this process over several days. Once a tassel has been pollinated, the ends of the silk strands will start to turn brown. As the cobs mature, you may have to net your corn crop as birds know when corn is perfect for eating.
Corn anthers won’t release pollen when conditions are too wet or very dry, the plants will wait until conditions are favourable. In areas of Australia that experience long periods of rain, it is best to plan your corn crop to avoid the wet season.