How to Grow Princess Flower

purple princess flower

The Spruce / LetÍcia Almeida

A native of Brazil, the princess flower (Tibouchina urvilleana) is a glorious addition to tropical and sub-tropical gardens and a a recipient of the Award of Garden Merit given out by the Royal Horticultural Society. This broadleaf evergreen has large purple flowers and soft hairy leaves that are red around the edges, adding interest and a burst of color to any landscape. Though princess flower is usually grown as a shrub in the U.S., it sometimes becomes large enough to form a small ornamental tree.

The leaves of moderate-growing princess flower are 2- to 6-inches long, and 1- to 1 1/2-inches wide. Its flowers are 3- to 5-inches wide, and a deep, vibrant purple. In the right climate, princess flower can produce blooms year-round, especially if it is deadheaded to encourage the formation of more flower buds. Its fruit is a small brown capsule, less than 1/2-inch long.

Use the princess flower as a specimen plant or for borders and foundations, it's best to plant it in the spring.

Botanical Name Tibouchina urvilleana (sometimes categorized as Tibouchina semidecandra)
Common Names Princess flower, glory bush, purple glory bush, lasiandra, pleroma, velvet-leaf tibouchina, and spider flower 
Plant Type Broadleaf evergreen shrub or small tree
Mature Size 6-8 ft. outdoors (occasionally to 15 ft.); 2-3 ft. 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
Flower Color Purple with red edges
Hardiness Zones Zones 9-11  (USDA); in zone 8, can be grown as perennial that dies back to the ground
Native Area Brazil
Toxicity Non-toxic to humans and animals
purple princess flowers
​The Spruce / LetÍcia Almeida
close up of a purple princess
​The Spruce / LetÍcia Almeida 
purple princess flowers
​The Spruce / LetÍcia Almeida 
pink princess flowers
The Spruce / LetÍcia Almeida

Princess Flower Care

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.

Light

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.

Soil

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.

Water

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 is a tropical plant and cannot tolerate a real frost: It will die back once a frost hits unless it's in a container that can be brought inside.

Fertilizer

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

You can propagate princess flower 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 ends 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 65-75 degrees Fahrenheit. Open the bag or remove the dome daily to mist the soil and cuttings.

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.

How to Grow Princess Flower From Seed

Princess flower is easy to plant from seed. If you've collected those seeds yourself, keep them in the fridge in a paper bag till it's time for spring planting. In a shallow seed tray, pour 2 inches of seed-starting potting mix. Moisten. Plant the seeds 1-inch apart, covering them with a thin layer of soil. Cover the container with a plastic bag, and set in a bright (but not directly sunny) area that won't get chilled. When seedlings are 2-inches tall, they can be replanted.

Potting and Repotting Princess Flower

Note the size of the princess flower plant that you want to repot, and size your container no more than 1-2 inches larger than the one your plant is currently residing in. Create a potting mix with peat-based soil and perlite, sand, or vermiculite, and wet it well. Scoop 1 to 2 inches of this potting mix into the bottom of your container, then place your princess flower on top. Be very gentle with this flower's roots! Fill in the rest of the pot with your potting mix, then prune the flower stems with a clean gardening shear.

Overwintering

Because they're tropical plants for tropical climates, if you want to keep your princess flower from dying back you can try bringing 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. After the last frost date has passed, it can be brought back outdoors.

Common Pests & 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.

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