Russian sage, known botanically as perovskia atriplicifolia, is a perennial flowering subshrub that throws tall spires of lavender-blue flowers during the summer and fall. Native to the Middle East and the Crimea, Russian sage is the epitome of a low-maintenance garden plant. It is not at all finicky about its soil conditions and will perform well in areas most plants would not.
Select a site for your Russian sage that has a full sun exposure and well-drained soil. Since Russian sage will thrive in most soil conditions no matter how poor, with the exception of wet heavy clay soil, no soil amendments or mulching are needed.
Water occasionally and deeply throughout the growing season in your area to maintain a lightly moist soil when feeling an inch or two down into the soil with a finger. Depending on your climate and size of your sage this may mean a few pints of water every few days or a gallon or more every two weeks. Just make sure not to over-water, as constantly wet soil will cause unattractive leggy growth and rot the roots. Russian sage is adapted to thrive in nutrient poor soil so fertilizing is neither necessary nor desirable.
Hard prune your Russian sage in the early spring before new growth appears. Hard prune with clean, sharp hand tools to correct spindly growth and promote a more compact, pleasing architecture for the shrub. Use your secateurs or loppers to shear off all the top growth foliage of the plant, leaving just 6 inches in height. New growth will then emerge from the base of the plant and new branching will grow from the remaining 6-inch branches. When the plant begins to leaf out again in the summer the overall effect will be a denser, healthier looking plant with entirely refreshed foliage.