Gardening Articles: Edibles :: Vegetables
Corn History and How it Grows (page 2 of 3)
by National Gardening Association Editors
How Corn Grows
Whether you're raising field corn, popcorn or sweet corn, they all grow basically the same way. Once the seed or kernel is planted in an inch or two of soil, it germinates in 5 to 12 days, depending on the variety and the soil temperature. Corn won't germinate if the soil temperature is below 55° F. It germinates fastest in soil that's 68° to 86° F.
After the seed sprouts, it sends down a taproot and starts to develop its first leaves. These leaves resemble blades of grass when they sprout.
As it grows, corn develops a thick, fibrous stalk and many flat, pointed leaves. The stalk can grow as tall as 15 feet, depending on the climate and variety. The roots of each plant grow down 3 to 5 feet and extend about 1 foot or so to each side of the stalk. Some of the roots develop above the ground. These are called "prop roots," and they serve as natural supports for the tall stalks.
When the stalk reaches about two-thirds its full height, its reproductive process starts. The plant first develops straw-colored tassels near the top. These are the "male" flowers of the plant. About three days after corn tassels, the silks or stigma of the "female" flowers appear lower on the stalk. These long, threadlike silks develop from the newly formed ears of corn. Each silk corresponds to a single kernel within the ear, and each kernel must be pollinated in order to have a completely filled ear. The tassels contain pollen that falls down and is carried to the silks by the wind. The tassels produce much more pollen than will ever be needed, and the silks flutter about in the wind to catch drifting pollen. The surface of each silk has tiny hairlike receptors to hold the pollen once it lands. It then travels down the silk to the kernel area, where fertilization occurs.
Although it's possible for a corn plant to fertilize itself, the pollen usually travels to the silks of neighboring plants. To ensure complete fertilization, it's best to plant corn in several short rows or blocks rather than long, narrow rows.
Even with nature's added insurance, pollination can be hampered by weather, soil conditions and poor fertility. That's why some ears may be completely filled and others may not.
Each corn plant generally produces one or two ears, except for special multieared varieties. Once pollination takes place, the kernels begin to develop on each cob. It usually takes about three weeks from silking for the first ears to be ready to harvest. The weather plays a big part here. The kernels develop fastest when the weather is hot and there's plenty of water. If it's too cool or too dry, the harvest will be delayed.