Salvia ‘Indigo Spires’ cannot be captured easily with a camera. Its spikes of flowers grow all season long, curling and twisting under their own weight like crazy fireworks in a deep, velvety shade of blue-purple that draws pollinators of all shapes and sizes. Even the calyxes that hold the flowers are purplish, which makes it look like it is blooming the length of the entire spike when the blossoms have dropped. About 40 years ago, a horticulturist at Huntington Botanical Gardens in San Marino, Calif., came across the plant, thought to be a bee-pollinated cross between two Mexican sages. The result was a sterile hybrid, which means it can be propagated only through cuttings.