A growing season is the period of the year when crops and other plants grow successfully. The length of a growing season varies from place to place. Most crops need a growing season of at least 90 days.

In tropical regions, where it is warm year-round, the growing season can last the entire year. In some tropical places, however, the growing season is interrupted by a rainy season. During this time, it is too wet to grow crops. Coffee, which grows in tropical climates, has this type of varied growing season. In Colombia, coffee is harvested all year. In Indonesia, heavy rains often interrupt the coffee growing season.

In other tropical places, it is sometimes too dry for crops to grow. The tropical region of northern Africa, called the Sahel, experiences frequent periods of drought. The Sahel is a transition zone between the Sahara Desert in the north and the savanna in the south. Due to dramatic weather patterns, the prospect of a successful harvest in the Sahel is highly uncertain.

In temperate regions, which have warm summers and cold winters, the length of the growing season depends mostly on temperature. Some growing seasons last as long as eight months. Europe and most of the Americas enjoy long growing seasons like this. The farther away a place is from the Equator, the shorter the growing season. In regions near the poles, the growing season is sometimes less than two months. The U.S. state of Alaska has an average growing season of only 105 days.

Elevation, or the height above sea level, also affects the growing season. This is because higher elevations usually have colder temperatures. High in the Sierra Nevada mountains in the U.S. state of California, the growing season lasts only 50 days, but along the state's southern coast, the growing season lasts 365 days.

There are two ways to determine the growing season. In temperate regions, the growing season is usually calculated by the average number of days between the last frost in spring and the first severe frost in autumn. The growing season can also be determined by the average number of days that the temperature rises high enough for a particular crop to sprout and grow. This measurement varies depending upon the crop. For rice to grow, the temperature must be at least 20 degrees Celsius (68 degrees Fahrenheit). Wheat, however, will sprout at just 5 degrees Celsius (40 degrees Fahrenheit).