1. Introduction & Taxonomy

Tibouchina grossa is a spectacular Brazilian shrub celebrated for its large, velvety purple flowers and distinctive felted foliage. Native to Atlantic Forest regions, this member of the Melastomataceae family creates a stunning display when covered in blooms that can measure up to 8 cm across. Its robust growth and extended flowering period have made it a favorite in tropical and subtropical gardens worldwide. Tibouchina grossa is notable for reaching 4.0 m in height, its red flowers.

A lovely, well branched shrub or small tree to about 4 m tall with dark green, soft, fuzzy leaves and masses of goblet shaped, carmine red flowers. Tibouchina grossa is native to low cloud forests and paramo of the Andes in Venezuela, Colombia and Ecuador between 2400 and 3800 m. It is very pupular with the many species of hummingbirds at this elevation. It is rare in cultivation but will make an outstanding ornamental in cool temperate climates such as Ireland, western Britain, New Zealand or the Pacific coast of the U.S., in short anywhere where the summers are not blistering hot and the winters are not freezing cold. Appearance Growth Form Small TreeShrub Ornamental Value Beautiful Uses Properties EvergreenFlowering Gardening LandscapingOrnamentalPotted

Taxonomic Classification

Habitat and Distribution

Tibouchina grossa is native to low cloud forests and paramo of the Andes in Venezuela, Colombia and Ecuador. It occurs naturally at elevations of 2,400-3,800 m. This species inhabits environments typical of the Melastomataceae.

Native Range & Distribution Map

The map below shows the native range and notable cultivation regions for Tibouchina grossa.

2. Biology & Morphology

Growth Form & Architecture

Tibouchina grossa is a tropical flowering shrub prized for its showy, often colourful blooms. The lush foliage and abundant flowers make it a centrepiece in warm-climate gardens.

Flowers & Reproductive Structures

Shrub flowers vary enormously across families, from tiny wind-pollinated catkins to large, showy insect-pollinated blooms. The flowers are red in colour.

Key Characteristics

• Height: 2-4 m
• Growth Habit: Erect Shrub
• Growth Rate: Moderate under optimal conditions
• Life Cycle: Perennial

3. Reproduction & Propagation

Primary propagation methods for Tibouchina grossa: Cuttings, seed, or layering (varies by species).

Propagation Methods

Semi-hardwood cuttings in summer, or softwood cuttings in spring. Air layering is effective for larger specimens. Seeds germinate readily in warmth.

4. Cultivation Requirements

Soil / Substrate

Rich, well-draining soil with organic matter. A mix of garden loam, compost, and perlite. Slightly acidic to neutral pH preferred.

Watering

Regular watering during active growth and flowering. Reduce in winter. Do not let soil dry completely.

Light Requirements

Full sun to partial shade. Most ornamental shrubs perform best with at least 4-6 hours of direct light daily.

Temperature

• Optimal Growth: 18-30°C (65-86°F)
• Minimum Tolerance: -12°C (10°F)
• USDA Hardiness: Zones 8-11

Pruning

Prune after flowering to maintain shape and encourage branching. Remove spent flowers to prolong blooming.

Fertilization

Apply a balanced slow-release fertilizer in spring. Most shrubs are moderate feeders.

Seasonal Care Calendar

Follow this season-by-season guide for optimal care timing throughout the year.

5. Diseases & Pests

Tibouchina grossa is generally robust and pest-resistant when cultural conditions are optimal.

Major Diseases

Root Rot (Phytophthora, Pythium)

Caused by overwatering or poor drainage. Ensure good drainage and avoid waterlogging. Improve soil aeration.

Powdery Mildew

White powdery coating on leaves. Improve air circulation, avoid overhead watering, and apply fungicide if severe.

Leaf Spot (various fungi)

Brown or black spots on foliage. Remove affected leaves, improve airflow, and avoid wetting foliage.

Common Pests

• Scale Insects — Hard or soft scales on stems and leaves; treat with horticultural oil
• Spider Mites — Fine webbing on undersides of leaves in dry conditions; increase humidity
• Mealybugs — White cottony masses at leaf axils; spray with soapy water or neem oil
• Aphids — Cluster on new growth; spray with soapy water or introduce ladybirds
• Whiteflies — Tiny white insects on leaf undersides; use yellow sticky traps

6. Indoor & Container Growing

Tibouchina grossa can be grown indoors in very bright conditions. Flowering may be reduced without adequate light.

Container Selection

Use containers with adequate drainage holes. Choose pots at least 5 cm larger than the root ball. Plastic retains moisture longer; terra cotta dries faster.

Indoor Light

Place in the brightest available location. Most shrubs need at least 4-6 hours of direct or bright indirect light.

7. Landscape Use & Design

Tibouchina grossa makes a dramatic architectural statement as a specimen, screen, or backdrop planting.

Design Applications

• Hedging & Screening: Dense shrubs for privacy, windbreaks, and boundary definition
• Foundation Planting: Soften building lines and define entrances
• Specimen / Accent: Showcase plants as focal points in the garden
• Mixed Border: Combine with perennials, grasses, and bulbs for year-round interest
• Topiary & Formal: Shape dense evergreens into geometric or sculptural forms

Companion Planting

• Perennials — Echinacea, Salvia, Lavandula for mixed borders
• Other Shrubs — Layer heights and textures for depth
• Grasses — Ornamental grasses add movement and contrast
• Ground Covers — Underplant with low-growing species for a finished look

8. Cold Climate Strategies

Tibouchina grossa shows good cold tolerance and can be grown outdoors year-round in many temperate climates.

Hardiness Thresholds

• USDA Zones: 8-11
• Minimum Survival Temperature: -12°C (10°F)

Overwintering Options

• In-Ground Protection: Apply 10-15 cm of mulch over the root zone before first frost. Wrap trunks of borderline-hardy species with fleece.
• Container Culture: Move potted plants to a frost-free garage, conservatory, or cold greenhouse for winter.
• Microclimate Selection: Plant against south-facing walls or in sheltered spots to gain 1-2 zones of extra warmth.

Frequently Asked Questions