Salvia x superba and Salvia x sylvestris -- two species that are very similar -- are both perennial blue sages and both are wonderfully long bloomers. They will start flowering in midsummer and continue through late summer if diligently deadheaded. Both have silver-gray leaves and wonderful purple-blue flower spikes growing 18 to 30 inches high, depending on the cultivar. They're drought-tolerant. Both are excellent for cutting and blend easily with many different flowers in the bed or border.
4 to 8
Soil and Light
Likes average, well-drained soil with moderate moisture. Full sun to part shade.
Plant established plants in spring in all zones or in fall Zones 7 and 8.
Fertilize by working in compost two or three times during the season or by applying a slow-release fertilizer, following label directions exactly. Tall types may need staking. Trim spent flower spikes as they fade in color to promote the growth of more flowers. It seldom needs division but it can be divided every few years if desired for more plants.