Russian Sage came out of no where, in the 1990s, and established itself as a garden standard. It's a sub-shrub grouped with perennial flowers because it blooms on new wood and it tends to die back to the ground each winter. Wait until the lower buds just start to turn green in the spring, then cut the whole plant down to 8 - 10 inches. As the flowers develop over the summer, their blue gradually increases in intensity until they are almost iridescent. After peak, they fade down to a gray blue.
Perovskia (Russian Sage) 'Blue Spires' (USDA Zones 4 - 9, 4' x 4', Purple/Blue Blossoms: July - Aug.)
Alternative
- Caryopteris x clandonensis 'Dark Knight' (USDA Zones 5 - 9, 4' x 4', Purple/Blue Blossoms: August)