Who was the Roman god of seasons, change, and plant growth?

The Roman god of seasons, change, and plant growth was Vertumnus.

Vertumnus represented transformation in the natural world, especially the changing seasons, ripening plants, gardens, and fruit trees. His name is linked in Roman interpretation with turning or changing, matching his ability to alter his form at will. His festival, the Vertumnalia, was celebrated on August 13.

The best-known myth about him appears in Ovid’s Metamorphoses. Vertumnus loved Pomona, a goddess devoted to orchards and fruit cultivation. Because she rejected suitors, he disguised himself as an old woman to enter her orchard. After praising Pomona’s work, he told her a warning story about the dangers of refusing love, then revealed his true identity; she accepted him.

Vertumnus was also honored at a shrine near the Forum Romanum on the Vicus Tuscus. A statue there was decorated according to the seasons, reinforcing his connection with cyclical change. He is distinct from Saturn, associated with agriculture and time, and Janus, associated with doorways and transitions.