The princess flower, sold as Tibouchina urvilleana or Pleroma urvilleanum (see the name change explained), is among the most popular flowering melastomes for warm gardens. Left alone, it can become tall and leggy. A little regular pruning keeps it compact and heavily flowered.
At a glance. Light: full sun to light shade. Soil: acidic, well-drained, rich in organic matter. Pruning: after flowering, plus light pinching in the growing season. Frost: leaves and tips are damaged by frost, and hardiness is limited, so protect in cold areas.
Choosing a site
Pick a spot with plenty of sun for the best flowering, ideally sheltered from strong wind, which can damage the large, soft leaves. In very hot climates, light afternoon shade helps. Plant it where you can enjoy the flowers up close, since they are large and velvety.
Soil
The plant prefers acidic, moisture-retentive but free-draining soil with generous organic matter. Heavy clay and alkaline soils cause yellowing and poor growth. Mulch to conserve moisture and keep roots cool. For more, see soil and fertilizer for melastomes.
Pruning step by step
Princess flower flowers on new growth, so regular pruning does not sacrifice blooms.
- Pinch young shoots during the growing season. Removing the growing tip encourages side branching and a bushier plant.
- Prune after the main flush of flowers. Cut back long, leggy stems by up to about a third, and remove dead or crossing branches.
- Rejuvenate old plants by cutting back harder in late winter or early spring in frost-free areas, just before new growth begins.
- Remove spent flowers to keep the plant tidy.
Always use clean, sharp secateurs. Avoid heavy pruning just before cold weather, since new growth is tender.
Frost and cold
Princess flower is a subtropical plant. A light frost may scorch leaves and tips, and a hard freeze can kill stems to the ground, though established plants in marginal climates sometimes recover from the base. In colder regions:
- Grow it in a container and move it under cover for winter.
- Plant against a sunny wall for extra shelter.
- Mulch the root zone thickly.
- Cover plants with horticultural fleece during cold snaps.
See winter care for tender melastomes for details.
Growing in containers
A large pot makes it easy to manage soil and winter protection. Use an acidic potting mix with good drainage, water regularly and feed lightly during the growing season. Repot as described in repotting a melastome.
Feeding
Use a balanced fertiliser formulated for acid-loving plants, applied lightly during the growing season. Too much nitrogen encourages leaves at the expense of flowers.
Making more plants
Stem cuttings root readily. The method is covered in propagating Tibouchina from cuttings. Cutting material is a useful by-product of pruning.
A note on invasiveness
Some Tibouchina-type plants and other melastomes have become weeds in certain warm regions. Before planting, check your local invasive species lists. See why some melastomes are considered invasive weeds.
Takeaways
- Pinch while growing, and prune after flowering for a compact, floriferous plant.
- Provide acidic, moist but free-draining soil.
- Protect from frost, or grow in a movable container.
- Do not overfeed with nitrogen.