The Slavic god of spring and fertility associated with the rebirth of nature is Jarilo.
Jarilo—also spelled Jarylo, Yarilo, Iarilo, Juraj, or Gerovit—is an alleged East and South Slavic deity of vegetation, fertility, youthful vitality, and springtime. His role reflects the seasonal return of growth after winter. The name is linked to the Proto-Slavic root *jarъ, associated with spring, strength, and vigorous life-force.
Evidence for Jarilo comes mainly from later folklore rather than extensive pre-Christian mythology. A 12th-century biography of Bishop Otto of Bamberg describes festivals for a war god named Gerovit; scholars commonly connect that name with Jarovit. Festivals called Jarilo survived into the 19th century in Ukraine, Russia, Belarus, and Serbia, usually in late spring or early summer. Related traditions included Croatia’s Jurjevo and Green George celebrations.
Jarilo is sometimes confused with Perun, Svarog, or Dazhbog, but those figures have different traditional associations. Jarilo’s identity is also debated because the surviving evidence is late and fragmentary, yet he is the standard answer for a spring-and-fertility deity in Slavic mythology.