Longwood Gardens By Denny Dyroff, Staff Writer, The Times Memorial Day Weekend is a time for mini-vacations, barbecues and traditional events. Longwood Gardens (Route 1, Kennett Square, 610-388-1000, www.longwoodgardens.org) will have an eagerly-anticipated special event this weekend. “Summer of Spectacle” will open on May 27 and run through September 30.