?Sierra Blue? is a tall  fast-growing lilac with a reputation for longevity. It can reach 15? ? 20? tall and 25? wide. Vivid blue flowers are produced from April to mid-May. This lilac is best grown in full sun and appears to do well on the coast as well as inland. Hybrid  F2; origin = seedlings (1948) University of California  Los Angeles from C. 'La Primavera' (C. cyaneus x   1935 SBBG) x C. cyaneus?; intro UCLA 1948