Crops can also be classified according to their thermo requirements.
The two major thermo groups are warm season and cool season.
Warm-season crops must have warm temperatures in order to live and grow.
They are adapted best to areas where freezing or frost seldom occur.
They also normally require longer growing seasons than cool-season crops.
Examples of warm-season crops are cotton,tobacco, field peas, and citrus.
Cool-season crops often need a period of cool weather in order to attain maximum production.
Most of the grains, tubers, and apples are cool-season crops.
Crops can also be classsifed according to their life spans.
They may be annual,biennial,or perennial.