Culture
Easily grown in average, dry to medium, well-drained soils in full sun. Prefers moist, humusy soils with good drainage, but also performs well in gravelly or sandy soils. Tolerates drought. Plants may repeat bloom throughout the summer, but need regular moisture to encourage this. Plants may spread somewhat rapidly in optimum growing conditions. Remove spent flower spikes to help extend the bloom period. Plants like cool night temperatures (best performance is north of USDA Zone 7). Plants may become somewhat floppy and open up as the summer progresses, particularly in hot and humid climates. If plants flop or otherwise depreciate in summer to the point where they look unsightly, consider cutting them back to the basal foliage. In any event, cut plants back after flowering has concluded. Propagate from softwood cuttings or division. Some hybrid wood sages are sterile, some will grow from seed but will not come true, and a few will come true from seed.
Noteworthy Characteristics
Salvia × sylvestris, often commonly called wood sage, is a hybrid perennial salvia that primarily results from crosses between S. nemorosa and S. pratensis. Some cultivars currently listed under S. × sylvestris have uncertain parentage, however, and may actually be cultivars of one of the parents rather than being hybrids. Moreover, The Plant List considers a large number of hybrids sold in commerce today under different names to be synonyms of S. × sylvestris, including S. × alpestris, S. × asperula, S. × collina, and S. × superba.
Salvia × sylvestris plants, by and large, are branched, upright, clump-forming, perennials featuring opposite, oblong to lanceolate, medium green leaves and showy spikes of tiny, tubular, two-lipped flowers (each to 1/2” long) which range in color from blue to lavender to purple. Flowers primarily bloom from late spring to early summer, but sporadic additional bloom may continue to appear throughout much of the remaining summer. Flowers bloom in 2-6 flowered verticillasters arranged in dense terminal racemes which rise well-above the basal leaves on square stems to as much as 30” tall. Subsequent to the primary bloom, sporadic additional bloom may continue to appear throughout much of the remaining summer. Leaves of this mint family member are aromatic, wrinkled and soft-hairy beneath with entire or serrate margins. Basal leaves (to 3” long) have petioles. Smaller upper stem leaves are sessile.
The genus name Salvia comes from the Latin word salveo meaning "to save or heal", in reference to the purported medically curative properties attributed to some plants in the genus.
Hybrid name of sylvestris comes from Latin meaning of or pertaining to forest or wood.
Wood sage has a variety of common names including violet sage, ornamental meadow sage, Balkan clary, purple flowering sage or perennial woodland sage.
‘Viola Klose’ features intense dark blue flowers on stems rising to 15-18” tall.
Problems
Some susceptibility to powdery mildew, leaf spot and rust. Spider mites, lacebugs, whiteflies, and scale are occasional insect pests.
Uses
Perennial borders, cottage gardens, butterfly gardens or wild gardens. Interesting accent. Effective in drifts or masses in mixed flower beds. Long-lasting cut flower.