The growing season of plants is primarily influenced by

The growing season of plants is primarily influenced by temperature.

Explanation:

The temperature of their environment, along with their species-specific temperature requirements have major impacts on plant growth. Plants usually grow more quickly with an increase in their environmental temperatures.

However, extreme temperatures (beyond their maximum and minimum) can slow growth. This determines their corresponding growth season, which includes: a seasonal interval between spring and autumn; or an average number of days above the minimum temperature. Every plant species has a specific range of temperatures:

An optimal temperature - for the best possible growth A Minimum temperature - (or basal temp) the lowest temperature capable of triggering growth A Maximum temperature - the highest tolerable temperature capable of triggering growth

E. g. Wheat's growing season requires sustained temperatures above 5°C.