Corn is only known in the cultivated state, and is believed to have originated in Mexico in prehistoric times. It is now distributed over the world and grown wherever summers are reasonably warm.
ECOLOGICAL ASPECT:
Corn is essentially a subtropical plant, but will grow now with its cultivars far into the temperate climate, as far north as Canada and Russia, where summers are long enough to produce good vegetative growth but rarely long enough to produce grain. It is known to grow from 58°N to 40°S latitude, and from altitudes below sea level to 4,000 m in the Andes. It is easily killed by frost. Most sweet corn is grown in areas with a mean temperature of 19–21°C during the summer months. Annual rainfall of 750 mm or more is required for adequate moisture. Deep, naturally rich, easily tilled soil is preferred. Corn grows on great variety of soil types. Ranging from Boreal Moist to Rain through Tropical Desert to Wet Forest Life Zones, corn is reported to tolerate annual precipitation of 2.3 to 41.0 dm (mean of 12.2 cases = 259), annual temperature of 4.9 to 28.5°C (mean of 19.2 cases = 258), and pH of 4.3 to 8.7 (mean of 6.4 cases = 175).