How to grow tibouchina
Overview
Tibouchina (Pleroma urvilleanum) is a dense, evergreen shrub grown for its large, velvety purple flowers and soft green foliage. It provides reliable mid-garden structure and links bolder feature plants together. Growers must protect it from frost and give it a warm, sheltered position.
Varieties
- Tibouchina urvilleana — The classic large-flowered form with deep purple blooms, widely grown in Australian gardens.
- Tibouchina 'Alstonville' — A compact, free-flowering variety with smaller purple flowers, ideal for pots and small gardens.
Soil Preparation
Tibouchina prefers slightly acidic to neutral soil (pH 5.5–7.0) that is rich in organic matter and drains freely. Before planting, dig in well-rotted compost and a handful of slow-release fertiliser. If soil is heavy clay, raise the bed or add gypsum to improve drainage.
Growing Guide
Plant tibouchina in a sheltered spot with morning sun and afternoon shade, or dappled light. Space plants 1–1.5 m apart. Dig a hole twice the width of the root ball, backfill with good garden soil mixed with compost, and water in well. Keep soil consistently moist but never waterlogged. Mulch deeply with organic mulch to keep roots cool and suppress weeds. Do not plant in heavy clay or low-lying frost pockets.
Care
Feed tibouchina with a balanced slow-release fertiliser in early spring and again in midsummer. Prune lightly after each main flowering flush to maintain shape and remove spent blooms. Renew mulch around the base annually to retain moisture and suppress weeds.
Companion Planting
Grow tibouchina with other warm-climate shrubs such as grevillea, camellia, gardenia, and murraya. Avoid planting near eucalypts or other trees that cast dense, all-day shade or compete heavily for moisture.
Common Pests & Risks
Scale insects and mites are the most common pests on tibouchina. Treat scale with a horticultural oil spray in late winter. For mites, blast plants with water or apply a miticide if numbers are high. Keep plants well-mulched and not stressed by drought to reduce pest pressure.
Troubleshooting
Yellow leaves: usually caused by overwatering or poor drainage. Check soil moisture and improve drainage. Brown leaf edges: often from salt burn or dry air. Water with rainwater and increase humidity. Leaf drop: can be from cold snaps or frost. Protect plants with frost cloth in winter. Sparse flowering: too much shade or lack of fertiliser. Move to a brighter spot and feed in spring.