The large, velvety leaves and vibrant purple, showy blooms have earned tibouchina (Tibouchina spp.) The name of glory blossom or glory bush. Native to South America, about 350 species of tibouchina exist, some with pink or white blossoms, but only a few species are under cultivation. Grow them outdoors in mild-winter, basically frost-free climates. In cold winter climates, grow tibouchina for a container plant that can go outdoors for the summer and inside for the winter, or as a greenhouse plant.
The most frequently developed tibouchina, glory bush (Tibouchina urvilleana) includes 3-inch-wide flowers that are a glowing, violet-purple. Also called princess blossom, the bush contains non-woody stems to 15 feet tall and 10 to 12 feet wide, growing in a mound. Heavy flowering occurs all during the summertime, with irregular flowering at other times of the year. Hardy in U.S. Department of Agriculture plant hardiness zones 9 through 12, the plant is killed back to the ground in zones 8 throughout the winter, but usually recovers the next spring. The cultivar “Athens Blue” (Tibouchina urvilleana “Athens Blue,” USDA zones 10 through 11) contains deeper purple blossoms.
A species with grayer, more velvety leaves, glory flower (Tibouchina grandiflora) is smaller compared to glory bush. It typically reaches 5 to 8 feet tall and 2 to 3 feet wide in USDA zones 9 through 11, although it can grow to 10 feet tall. Its smaller, royal purple blooms occur in spring, summer and fall in showy panicles, which can be loosely-branching clusters of blossoms, atop blossom stalks that rise above the leaf. Cut off the old flower stalks to showcase the dramatic leaf once the plant isn’t in bloom.
Capable of being educated as a little tree and with the name glory bush, Tibouchina lepidota has regal purple blossoms that nearly fully cover the bush to get a few weeks throughout the summer. Hardy in USDA zones 10 through 11, in warm winter climates it blooms nearly annually. The taller-growing purple glory tree (Tibouchina granulosa, USDA zones 10b through 11) grows 10 to 15 feet tall and may reach 20 feet. For a tree, this is actually the tibouchina of selection. Panicles of all 2-inch-wide, purple flowers appear in spring, summer and fall. Grow it as a shrub or prune and shape it if it’s young to form a tree.
Reflecting their tropical origins, tibouchinas need moist but not soggy conditions and also an organic-rich, well-draining dirt. Grow glory bush in full sun except in regions with hot summers, where it conquers daytime shade. Prune the trees to keep them to shape and size after they’re done blooming; use pruning shears cleaned with a cloth soaked in rubbing alcohol to prevent disease spread. In spring, apply a controlled-release fertilizer to the soil around the base of the plant, evenly scattering it under the branches and out a little past the drip line. Mix it into the upper layer of dirt and water well. Use a product such as 15-9-12 at the rate of 1.3 lbs per 100 square foot of landscaping area. Tibouchina are almost pest- and disease-free. They are classified as invasive in Hawaii, in which they seed into native habitats. Remove seed pods so seedlings can’t volunteer should youn’t want tibouchina to propagate.