Combining botany, lore, and personal opinions, lilac specialist Jack Alexander will present a sweeping overview of lilac care, culture, and history on Tuesday, May 8, from 4 – 6 at the Arnold Arboretum. Youâ€™ll learn when to prune your lilacs, how to rejuvenate them, and what their optimal growing conditions are. Jack will show examples of various growth and flower forms and point out examples of the best lilacs for fragrance, disease resistance, color, and length of flowering season as you walk in the Arboretumâ€™s extensive lilac collection. Come with questions and a clipboard and paper for note-taking. Be prepared for rigorous walking since the Arboretumâ€™s lilac collection is located on steep terrain. Meet at the Dana Greenhouses at 4:00 to walk to the lilacs with the instructor. Rain date: Thursday, May 10. Fee $20 Arnold Arboretum member, $25 nonmember.Â Register on line at www.my.arboretum.harvard.edu.