Purple flowers will burst from along the length of this young inflorescence as it grows. Click to download a large version (800x600).
Indigo Spires is one of the most dependable butterfly magnets you can grow. This is a very long flowering perennial with distinctive elongate, inflorescences of blue-violet flowers and purplish calyces. The flowering spikes can be up to 1 ft (0.3 m) or more in length with whorls of half-inch (1.3 cm) flowers all along their lengths. They bend down under their own weight. The calyces persist after the corollas have dropped off. The plant has a sprawling habit, getting about 3-5 ft tall and spreading out even more. The leaves are about 3 in (7.6 cm) long and coarsely toothed. Indigo Spires starts blooming in early summer and continues unabated until the first frost.
This striking Salvia was discovered growing at Huntington Botanical Gardens in California in the 1970s. It is believed to be a hybrid between two species that were growing in the vicinity: S. farinacea and S. longispicata, both of which are native to Mexico. Salvia 'Indigo Spires' was introduced to gardeners in 1979, and has become one of the most popular of all the cultivated sages.
Indigo Spires tends to keep growing and growing and then falling over under its own weight. Constant pruning and pinching will keep it in bounds, and removing the flower spikes after most of the flowers have dropped off will encourage more blooming.
Light: This salvia does best in full sun, but does okay in part shade, too. Moisture: Indigo Spires needs regular watering to be at its best, but can tolerate drought if it has to. Hardiness: USDA Zones 7 - 11. Indigo Spires dies to the ground after frost and returns reliably in spring. Propagation: Indigo Spires is a sterile hybrid, so don't bother with seeds. Fortunately, it is very easy to root from cuttings.
Steve's big bed of 'Indigo Spires' salvia is a beautiful background for the beebalm (Monarda didyma) in the forground and the pink poppies (Papaver somniferum) in the background - those flowers may fade but the salvia will continue to bloom until frost.
Indigo Spires is one tough plant - it loves neglect and thrives in heat and humidity. I have a stand of Indigo Spires and blue anise sage (Salvia guaranitica) that is left to its own devices and allowed to sprawl all summer. It may look a little unkempt at times, but the flowers just keep coming and the hummingbirds and butterflies love it. It's usually covered with long-tailed skippers and native bumblebees.
John MacGregor, horticulturist at Huntington Botanical Gardens in California, described his lucky find as a "sterile hybrid, courtesy of the bees." He gave it the horticultural name, 'Indigo Spires'. This particular hybrid does not have a botanical name, hence no capital X and no italics. (See Floridata's Fact Tract, What's in a (Plant) Name, for more about how plants get their names.)
There are more than 700 species of Salvia and many people consider them among the finest of garden perennials.