Everybody loves this plant. In fact, Salvia May Night is one of the most popular perennials of all time, up there with Rudbeckia Goldsturm and Sedum Autumn Joy. No garden should be without this one.
About Salvias: Salvias can be confusing. Everybody knows those fire-engine red spires we see in park plantings every summer. Well, they're the annuals. Were dealing here with perennials. And most perennial Salvias bloom blue or purple, and most are much larger plants than the little red annuals.
Growing with numerous dense flower spikes that come into full bloom in May or June, the cultivars of S. nemorosa (which is a combo of several European species that are winter hardy) have become the favored ones for perennial gardens. Some people call them Sage. Some just call them Salvias. But everyone who grows them loves them in the garden. Here are the best-known classic cultivars:
Sensation Rose is the rich red growing up to about two feet.
May Night is the very popular taller one with the signature deep purple Salvia color, to 3 feet.
Snow Hill is the rather short, but popular white, growing only to about 20 inches.
These famous Salvias , growing together or in single stands, are sure color every season in your perennial garden.
About warmer zones: Famous perennial guru Allan Armitage, who gardens in the south, warns that these Salvias may survive all the way to zone 9, but he says from Zone 8 south, they flop over terribly, making problems for the gardener, while further north they stand tall and straight. He heartily recommends them for gardeners in colder zones.