Native to India, blue sage is a large, tender shrub that's prized in central and south Florida and the Rio Grande Valley for its showy flowers of celestial blue. It grows fairly quickly into an open, upright plant about 45 feet high and half as wide. Deep green, prominently veined leaves reach 8 inches long. In winter, spikes of intensely blue, 34- to 112 inches-wide blossoms, attractive to butterflies, appear along the branches and at their tips. Blue sage prefers sandy, well-drained soil of moderate fertility; it does not tolerate salt spray. If frost kills branches, cut shrub to the ground; new growth will emerge with the advent of warm weather.