Plants with grey foliage were prized by Gertrude Jekyll, one of the best known English gardeners of all time. She taught us that grey, silver plants soften the landscape if used wisely.
Perovskia is a genus of only four species, and the best one is the native of Pakistan "Perovskia atriplicifolia," which has small blue flowers on branching grey stems that grow up to four feet tall.
Since it can also grow four feet wide, this aromatic sub shrub is a commanding presence in the garden. One can be a focal point, and a grouping can create an impressive effect with a haze of blue when the plants bloom and skeletal silver architectural shapes in the fall and winter.
The common name is Russian Sage. Bloom begins in July and continues through September.
Do not cut down or prune these sub shrubs until they begin to grow in summer. Then you can distinguish old wood from new growth.
These plants are hardy, love sun and heat and are drought and pest resistant. I have read that they combine well with other perennials, but in my garden I have found that they do best if they have plenty of room. So I prefer them in a place where they are planted on their own where they can show off their statuesque charm without competition. I encourage them to be prima donnas.