Most corn plants should be managed to produce a single ear. Multiple earing occurs on sunny outside rows and where population is low. Some hybrids also tend to put out a second and sometimes a third ear. Hybridization also makes the plant bigger and more stress resistant. Virtually all corn grown in the U.S. and in eastern Canada is hybrid corn.
Maturity is the most important consideration when choosing a hybrid.
For grain, hybrids should be planted that can be expected to mature and dry down. Corn is normally harvested at 20 to 30 per cent moisture and requires drying for safe storage. Since they do not need to produce dry kernels, silage growers should plant later hybrids, to maximize their use of the growing season. In Canada, corn maturities are rated with a system called heat units. Top-producing grain corn hybrids are currently readily available for southern Manitoba and selected other areas in Saskatchewan and Alberta.