A native of Brazil, the princess flower (Tibouchina urvilleana) is a glorious addition to tropical and sub-tropical gardens. This broadleaf evergreen has large purple flowers and soft hairy leaves that add interest and a burst of color to any landscape. Though princess flower is usually grown as shrub in the U.S, it sometimes becomes large enough to form a small ornamental tree. It can also be used as an indoor container plant in cooler regions if full light and warmth are provided.
The leaves of princess flower are 2 to 6 inches in length and 1 to 1 1/2 inches wide, covered in soft hair and often tipped with red around the edges. The flowers are 3 to 5 inches wide and a deep, vibrant purple. Princess flower can produce blooms year-round, especially if it is deadheaded to encourage the formation of more flower buds. The fruit is a small brown capsule that is less than 1/2 inch long.
Use the princess flower as a specimen plant or for borders and foundations. The large vibrant purple flowers and soft hairy leaves work well in sensory gardens. This shrub is a recipient of the Award of Garden Merit given out by the Royal Horticultural Society.
|Botanical Name||Tibouchina urvilleana (sometimes categorized as Tibouchina semidecandra)|
|Common Names||Princess flower, glory bush|
|Plant Type||Broadleaf evergreen shrub or small tree|
|Mature Size||6 to 8 feet outdoors (occasionally to 15 feet), 2 to 3 feet indoors|
|Sun Exposure||Full sun (prefers some afternoon shade in the hottest zones)|
|Soil Type||Rich, well-drained, acidic soil|
|Soil pH||7.0 or below (acidic to neutral)|
|Bloom Time||Year-round seasonal bloomer|
|Hardiness Zones||Zones 9 to 11 (USDA); in zone 8, can be grown as perennial that dies back to the ground|
How to Grow Princess Flower
Grow princess flower in rich, fertile soil that is well-drained, in a full sun location. Be sure to protect this plant against frost and strong winds. If you live in a cooler USDA zone, you can plant the princess flower in a container to be brought in each winter, provided you are able to provide it enough warmth and light.
Princess flower has a natural round or vase-shaped growth habit, and it is quite tall when mature. Many gardeners prefer to prune it to control its size and shape it into a more compact form.
The princess flower prefers full sun but can tolerate partial shade, provided it still receives at least five hours of direct sunlight each day. In fact, if you are in a particularly hot area, it's a good idea to provide some shade.
Your princess flower will appreciate damp, rich soil. While the plant does need regular watering, it's important that the soil drains well; princess flower can experience root rot if the soil is soggy. This plant prefers a slightly acidic soil, which can be provided through soil amendments such as peat moss, or by feeding it with an acid fertilizer.
Princess flower is somewhat tolerant of drought but does best when regularly watered. Unless it's very hot, weekly watering is sufficient (no more than 1 inch of water per week, through a combination of rainfall and irrigation). Be careful to avoid overwatering, as very wet soil can injure the plant.
Temperature and Humidity
Princess flower cannot tolerate a real frost and will die back once a frost hits. If you want to keep your plant from dying back you can bring it indoors for the winter. One option is to cut a potted plant back to about 8 inches and keep it in the garage or basement. If you do keep the plant in the dark, water it only enough to keep it from drying out.
It's best to fertilize your princess flower each spring, summer, and fall. You can use fertilizer intended for acid-loving plants such as rhododendron or azalea, but your plant will also appreciate a bit of manure. Mulching will help your princess flower to retain moisture.
Pruning Princess Flower
Like most shrubs, princess flower should be pruned to remove dead or damaged branches whenever you spot them. Beyond this, pruning is usually done to maintain a rounded shape, or to train it into standard if you prefer a tree shape. Any pruning is best performed immediately after the shrub finished blooming.
Pinching off new growth will encourage branch formation and make the shrub fuller.
Propagating Princess Flower
The easiest way to propagate princess flower is by rooting softwood cuttings:
Cut 4-inch lengths of soft green stem, making the cut just below a leaf node. Remove the leaves from the bottom half of the stem, then dip the end into rooting hormone. Plant the cutting into a container filled with a seed-starter mix, then cover the container with a large plastic bag or plastic dome.
Place the cutting in a bright area out of direct sunlight, with temperatures between 65 and 75 degrees Fahrenheit. Open the bag or remove the dome daily to mist the soil and cutting.
After 10 to 12 weeks, the cutting should be sufficiently rooted so that it can be potted up or planted in an outdoor garden location.
Common Pests and Diseases
Occasionally scale, nematodes, aphids, mealybugs, and geranium budworm may attack princess flower. To manage these, you can introduce beneficial insects such as ladybugs, or spray your plant using insecticidal soap or horticultural oil.
Mushroom root-rot can occur if a princess plant is kept in soggy soil. To avoid this problem, water no more than once a week and check to be sure that your plant is not receiving too much rain. Never water a princess flower shrub is if it already receiving adequate weekly rainfall.