Natalie Pfanstiehl will lead a watercolor workshop at Watson Farm on Saturday, Sept. 9, from 9:30 a.m. to 3 p.m. Pfanstiehl will give a one-hour demonstration of landscape painting. She will spend the rest of the day assisting students with composition and technique. Students should bring their own painting materials and lunch. All levels of experience are welcome. Cost is $25 for Historic New England members, $40 for nonmembers. Register by calling Heather Minto at 423-0005.