Tropical shrubs with purple flowers can add a rich dimension to any garden landscape. While best suited to areas where temperatures remain above freezing, many tropical shrubs will re-sprout in the spring after a killing frost. Purple flowering tropical shrubs provide eye-catching contrasts to yellow or orange plantings..
Purple Princess Flower
Native to Brazil, Purple princess flower (Tibouchina urvilleana) brings glorious blue-violet summer color to gardens in warm climates, and continues to bloom sporadically in other seasons. The dazzling 3-inch flowers contrast with its red-tinged green leaves. Princess flower's spreading habit, if left unchecked, produces 10- to 12-foot high-mounds of blooming stems that extend up to 15 feet wide. Pruning the shrub, says Floridata's publisher Jack Scheper, will control its shape.
Princess flower does best in rich soil, and thrives with regular watering and mulching. It likes sun with afternoon shade. Princess flower likes to be kept moist but can tolerate short dry spells and is suitable for US hardiness Zones 8 through 12 (a minimum temperature of 10 degrees F). The plant dies back in sub-freezing temperatures, re-sprouting with the return of warm weather.
Native to the southern US coastal plain, Carolina wolfberry (Lycium carolinianum) is a thorny evergreen shrub. Its branches, produce succulent foliage, light purple 1/2-inch blossoms and the red berries for which it's named. Its exceptionally long blooming season continues from April to October.
Salt-tolerant Carolina wolfberry likes a sunny to partly shady location with moist sandy, gravelly or loamy soil. It will survive in standing water for long periods. The plant's edible berries have a tomato-like flavor. Extract their seeds for planting, or buy started bushes at nurseries.
Mexican Bush Sage
A member of the mint family, Mexican bush sage (Salvia leucantha) is an evergreen native of Mexico and Central America. Hardy in frost-free areas, Mexican bush sage has a spreading habit. It forms mounds up to 4 feet high and wide with 1-inch willow-like leaves.
Throughout the fall and winter--or until a freeze--Mexican bush sage produces clusters of purple-blue calyxes with small white flowers. The calyces in each cluster far outnumber the flowers, giving the bushes a definite purple appearance. Some cultivars of the shrubs have purple flowers and calyces.
A sun lover, this plant becomes leggy if it gets too much shade. When grown as an annual, it doesn't flower until late summer or early autumn. Propagate Mexican bush sage from root or stem cuttings and cut it back in the early summer to promote bushiness. Un-pruned bushes may become top-heavy with bloom, causing their flowers to break off. Its silver-gray foliage, attractive throughout the growing season, makes Mexican bush sage a good choice for hedges.