Russian sage, (Perovskia atriplicifolia), is a woody perennial that you may naturalize in large groupings or grow as a singular specimen. Silvery-white stems are lined with sage's gray-green leaf. From July until October up to zone 5, the tall willowy stems bear clusters of lavender-blue flower spires. Pruning will keep Russian sage aesthetically pleasing as well as provide healthy new growth to rejuvenate the plant.
Procure a pair of hand-pruning shears. A sturdy pair of hand pruners is your best friend in the garden when it comes to manicuring woody shrubs and plants such as Russian sage. Stems may grow tough with age and the older stems are most likely to be your target.
Take a visual inventory of your Russian sage. The natural habit of this plant is to grow tall and willowy, as well as wide and profuse with lateral stemming. Determine whether you want the sage to fit into your garden plant as a tall manicured specimen, or lend itself to a free-form hedge style. This will help you decide how extensively to prune.
Prune Russian sage prior to the end of dormancy and before spring is in full swing. Use the process horticulturists refer to as "rejuvenation." Early spring pruning will enhance the health of your sage regardless if you plan to do further aesthetic pruning for a manicured formal garden.
Get your shears down to the base of the plant. Target older woody stems to cut away and leave the young new stems. New flowering and growth will take place on newer shoots. As late as April, you may trim back the entire plant back to 6 inches tall if your plant is at least 12 inches. Refrain from such radical pruning during the active flowering season.
Pinch back up to a third of the stem tops with your fingers that you find aesthetically displeasing during the growing season. This will help keep the manicured look if you prefer that, while not causing the plant a shock to its system by radical pruning during growing season.