Gardening ideas and insights about the origin of food will be the topic of Arlington’s fourth annual EcoFest, to be held from 10 a.m. to 2 p.m. March 31 in Town Hall. The free event, titled “Locavoracious . . . about food,’’ is a collaboration involving local officials, the Arlington Garden Club and the Vision 2020 Sustainable Arlington Committee. Featured speakers include Charlie Radoslovich, an urban farmer who will discuss his approach to farming small plots of land to provide fresh, nutrient-rich vegetables, and author Frances Moore Lappe, whose newest book is “EcoMind: Changing the Way We Think, to Create the World We Want.’’ For more information, contact Patsy Kraemer at 781-858-8629. - Brock Parker