The City of Mission Viejo is hosting its annual Earth Day and Arbor Day Celebration with a planting and Green Expo from 8 am to noon on Saturday, April 26. Volunteers will have the chance to embrace nature by planting trees and shrubs along the section of Oso Creek Trail that is north of Jeronimo Road. Participants should wear a hat, gloves, boots and sunscreen. Lunch and ice cream will be available for volunteers while supplies last.