In the United States, tibouchina is not normally thought of as a houseplant. In fact, outside of the subtropical zones where it's often used as a landscape plant (including its native Brazil), it's not thought of much at all. This is a shame, as the beautiful plant boasts striking purple flowers, silvery velvet leaves, and an open growth habit.
Also known as glory bush or princess flower, tibouchina can be started and grown year-round for those flower fans that do not live in the proper climate to host the plant outdoors. Though not terribly difficult to grow indoors, the plant is particular about a few of its conditions. If you can meet its requirements, you'll have a wonderful, novel houseplant that will grow moderately quickly and can last for a long time. (It can add as many as 36 inches in a year outdoors, though it will likely be fewer when kept indoors.) Annoy it, and you'll have a floor littered with dead leaves and a very unhappy plant.
|Botanical Name||Tibouchina granulosa|
|Common Name||Tibouchina, purple glory tree, glory tree, princess flower|
|Plant Type||Evergreen shrub|
|Mature Size||10-20 ft. tall, 6-10 ft. wide|
|Sun Exposure||Full sun|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Spring, summer|
|Hardiness Zones||9–11 (USDA)|
|Native Area||South America|
There are likely two potential reasons tibouchina isn't more widely used. For starters, it does need some trimming to control its growth habit—sprawling tibouchina is leggy and not especially attractive. Second, they seem to have a fairly narrow margin for error: Leaf drop and plant decline are unfortunately common, often because of watering or temperature issues.
In ideal circumstances, tibouchina thrives in a Mediterranean-like climate, with moderate temperatures and water. If exposed to cold drafts or strong sunlight, expect the plant to start dropping leaves. Additionally, tibouchina is not very susceptible to pests.
Even if you have trouble keeping Tibouchina alive over the long haul, they make wonderful display plants for their blooms and will provide a season of color indoors before they decline. Provide the tibouchina with these prime growing conditions, which will allow it to flourish indoors.
Tibouchina prefers bright, filtered sunlight. In general, direct summer sunlight is just a bit too strong, but it will not flower correctly without at least six to eight hours of bright light a day. Choose a place in your home that received consistent diffused light, or move the plant around your home periodically if necessary.
Plant your tibouchina in a loose, well-drained potting soil mixture. You want to keep your plant from becoming waterlogged, so choose a pot that has ample drainage in its base.
Keep your plant regularly moist during its growing season and throughout the summer—a deep weekly soaking should work fine. You can reduce your watering cadence in the winter months, but you should never let your plant dry out completely.
Temperature and Humidity
Tibouchina flowers in the late spring or mid-summer. They'll do well with little environmental fluctuation and should be kept in temperatures around 70 degrees Fahrenheit. Tibouchina disikes extreme hot or cold temperatures and should be kept away from any harsh drafts or breezes.
In addition, tibouchina loves a humid environment. Keep the plant in a naturally-humid part of your home, like the kitchen or bathroom. If necessary, you can spritz the plant daily, or invest in a small space humidifier.
Feed your tibouchina plant during its growing season with liquid fertilizer or a controlled-release fertilizer, used according to label instructions.
Tibouchina can be propagated from semi-woody cuttings, preferably with rooting hormone. Because the plant is a tropical, cuttings are best held at warm temperatures (around 80 degrees Fahrenheit) and high humidity. They do best in a propagation house or covered terrarium-type setting. Even then, you may find that tibouchina cuttings can be difficult to root.
Potting and Repotting Tibouchina
Tibouchinas naturally grow to small trees, with a loose, open growth habit ranging up to 20 feet. In the home, the first rule of thumb is to keep your tibouchina closely trimmed by pinching off new growth shoots and gently shaping the plant to contain its sprawling growth. This will likely slow down its growth and reduce the frequency of repotting. When you do repot the plant, go up one pot size and use fresh soil.
Common Pests/ Diseases
Like many household plants, tibouchina plants can come down with issues ranging from scale and spider mites to aphids. While these pests are typicaly kept under control in nature thanks to natural predators, you will need to deal with them promptly indoors.
Move your infected tibouchina plant away from the rest of your houseplants and treat it with a mild insecticide or horticultural oil like neem oil.