The small Brazilian tree known as Purple Glory (Tibuchina granulosa) thrives only in U.S. Department of Agriculture plant hardiness zones 10 and higher. If you're lucky enough to live in a Mediterranean or subtropical region, the distinctive tree, with its vivid purple flowers, makes a striking specimen tree or shrub border addition. The main upkeep involved in tending Purple Glory involves maintaining acidic soil and practicing careful pruning to create the classic upright shape that best shows off its flowers. Purple Glory is pruned after its first spring flowering to promote a uniform shape and to encourage a fresh flush of flowers on the resulting new growth.
Plant Purple Glory in an area in which it will receive full sun and which has been tilled and lightened with peat moss to improve drainage and add acidity. Space the tree to accommodate its mature spread of 15 to 20 feet.
Mulch the tree to about 1 foot beyond its drip line, the ground directly below the tree's outermost branches. As Purple Glory grows, extend the mulched area. Use a 3- to 4-inch layer of wood chips or ground bark, allowing a circle of bare soil extending a few inches from the trunk in all directions.
Water the Purple Glory tree at least once a week during periods of low rainfall, aiming for 1 inch of water per week. Keep the soil moist, but not wet, throughout the root zone.
Fertilize Purple Glory in early spring, before it begins to flower. Use an organic or synthetic plant food geared toward acid-loving plants and follow package directions for the amount and method of application.
Pinch off side growth from branches to ensure a bushy, rather than weedy, overall shape. Removing these side twigs encourages the tree to put its energy into producing more plentiful main branches.
Remove branches that cross in front of other branches or that are weak looking, especially in the first few years of Purple Glory's life. This early pruning results in a stronger, straighter trunk.
Prune lower branches throughout its lifetime so that the Purple Glory maintains an upright, rather than drooping, shape.
Monitor your Purple Glory for signs of scales, which resemble raised circular or oval bunches on the tree's trunk or branches. Some types secrete "honeydew," a sticky substance which can lead to sooty mold. Other signs include curling or brown leaves and cracked trunks.
Spray horticultural oil on Tibuchina granulosa if the tree appears to be heavily infested with scales. Follow package directions for application methods and timing. In general, horticultural oil should be used in cooler months, before the flowering period.
Things You Will Need
- Peat moss (as needed)
- Wood chips or ground bark
- Hose or drip irrigation system
- Fertilizer for acid soil plants
- Pruners or loppers
- Horticultural oil (as needed)
- Tibuchina granulosa prefers acidic soil. If your pH level is higher than 7.5, lower the pH by adding sulfur or peat moss -- both available at garden centers -- to the soil before planting. Soil-testing kits are also available at garden centers, and will tell you the pH level of the ground you intend to plant Purple Glory both before and after treatment.
- Along with scales, Tibuchina granulosa is vulnerable to nematodes, tiny worms that live in the soil. Above-ground signs of nematode damage in trees includes early leaf drop, stunted growth and failure to thrive. Your local extension service may be able to analyze a soil sample to confirm the existence of nematodes. No pesticides currently exist to treat the microscopic pests, but proper watering and feeding of your Purple Glory tree may keep it strong enough to avoid serious damage.