Introduction

Carmona retusa, the Fukien tea tree, is one of the most widely grown tropical indoor bonsai subjects, prized for its small, dark-green leaves with white spots, continuous production of tiny white flowers, and small red-to-black berries that appear year-round in warm conditions. Native to southern China, the Philippines, and Southeast Asia, it demands consistent warmth and high humidity and performs poorly when moved or subjected to cold drafts — leaf drop and dieback follow environmental changes within days. Whitefly is its most persistent and troublesome pest, requiring vigilant monitoring. Despite its sensitivity to placement changes, Fukien tea rewards stable warm conditions with rapid, dense growth and reliable flowering.

Carmona retusa (syn. Ehretia microphylla) is a tropical shrub or small tree reaching 3-8 m in the wild, native to tropical Asia from southern China through the Philippines, Malaysia, and into northern Australia. The leaves are 1-3 cm long, dark glossy green with distinctive white dots (raised glands or cystoliths) on the upper surface, and rough to the touch due to stiff hairs. Flowers are tiny, white, 5-petaled, borne in small axillary cymes throughout the year in warm conditions; they are mildly fragrant. Fruits ripen from green through yellow-orange to red and finally black, and multiple stages of fruit development are visible simultaneously on a healthy tree. Bark on old trunks is grey-brown with shallow, irregular fissuring that develops attractive character over many years. The species is placed in family Boraginaceae following modern molecular classification.

History & Tradition

Fukien tea bonsai has a long history in southern Chinese penjing tradition, where small-leaved tropical trees with year-round flowering and fruiting are particularly valued. The species name references Fujian (Fukien) province, a major center of Chinese penjing practice. In the West, Carmona gained popularity from the 1980s onward as the global trade in mass-produced indoor bonsai expanded — it became one of the most commercially sold indoor bonsai species worldwide. Despite this mass-market association, correctly grown Fukien tea bonsai of genuine quality are respected subjects in tropical bonsai exhibitions.

About Broadleaf Evergreen Bonsai

Broadleaf evergreen bonsai maintain year-round foliage while offering the leaf detail and trunk character of deciduous trees. Boxwood (Buxus) develops exceptionally dense foliage that can be refined into precise cloud-like pads. Olive trees (Olea europaea) bring Mediterranean character with their silver-green leaves and ancient-looking hollowed trunks. Ilex (holly) species offer dark glossy foliage and occasional berry displays. Privet (Ligustrum) grows vigorously and tolerates heavy styling, making it a productive training species. Camellia bonsai provide winter flowering combined with glossy, architectural foliage. These species generally tolerate shade better than conifers and deciduous trees, making them versatile additions to any collection.

Botanical Profile

Carmona retusa (Vahl) Masam. syn. Ehretia microphylla Lam., family Boraginaceae. The white-dotted leaf surface is a consistent diagnostic feature distinguishing it from similar-sized tropical bonsai species. Chromosome number 2n=36. The species is self-fertile and sets fruit prolifically under good light conditions. Despite being widely sold as an indoor bonsai in temperate countries, Carmona is a genuinely tropical species with no cold tolerance — temperatures below 10°C cause leaf drop and root damage; below 5°C is potentially lethal. The correct current name Carmona retusa is used in scientific literature; Ehretia microphylla remains common in the nursery trade.

Bonsai Styles

Informal upright is the dominant and most natural style, reflecting the species' spreading, irregular growth habit in tropical forests. Slanting style works well with trunk material that has developed natural lean. Broom style suits Carmona because the naturally spreading branching produces a rounded canopy reminiscent of a mature tropical shade tree. Semi-cascade works on material with naturally pendant growth. Formal upright is rarely pursued as the growth habit fights against strict vertical structure. Multi-trunk and clump styles are effective where multiple stems arise from a common root base. The small leaf size makes Carmona suitable at all scales from shohin upward.

Group Style Guide

Literati (bunjin) style suits boxwood and olive, emphasizing their naturally sparse, aged character. Informal upright is the most versatile style for broadleaf evergreens, accommodating various trunk shapes. Olive bonsai often develop hollowed trunks that suit dramatic driftwood and deadwood features. Root over rock works well with fig and privet species that develop strong surface roots. Broom style (hokidachi) is effective for dense-growing species like privet and boxwood. Multi-trunk and clump styles suit species that naturally produce basal shoots.

Trunk & Nebari

Carmona develops surface roots readily in tropical conditions, and good nebari is achievable within five to eight years with consistent root-combing during repotting. The grey-brown bark on established trunks develops shallow fissuring and corky texture at the base that adds significant age character. Trunk thickening is moderate — ground-growing in tropical climates accelerates development considerably. In temperate cultivation, trunk thickening is limited by the necessity of container growing year-round. Air-layering below interesting nebari features can reposition the planting level to expose surface roots.

Deadwood Techniques

Deadwood on Carmona is used sparingly — the relatively soft wood decays quickly in the humid conditions the tree requires for health. Small jin on branch stubs can add character but should be treated with wood hardener and lime sulfur to retard decay. Shari on the trunk is rarely developed due to the decay risk. Where deadwood is maintained, inspect regularly for signs of decay advancing into the live wood and trim back to sound material if necessary. The focus on Carmona bonsai is the living canopy, fruit, and flower display rather than deadwood features.

Wiring & Shaping

Aluminum wire is standard for Carmona due to the relatively soft, pliable wood that takes bends easily without cracking. Wire during the growing season — the wood is more flexible when the tree is actively growing. Branches up to 8 mm diameter can be bent freely with gentle pressure; larger branches should be worked over multiple seasons. The rapid growth in warm conditions means wire must be checked every four to six weeks to prevent bite — Carmona's thin bark scars permanently if wire is left too long. Guy wires on major lower branches avoid the wire-removal challenge on crowded foliage.

Pruning & Pinching

Pinch new growth regularly throughout the growing season by removing the leading pair of leaves once a shoot has extended two to three internodes, leaving two leaves to develop ramification. Carmona responds well to hard pruning, back-budding reliably from two-year-old wood. Structural pruning at any time of year is possible in a stable warm environment. Avoid major pruning and repotting simultaneously — the tree's sensitivity to stress means one significant intervention at a time. Maintain interior light by periodically thinning dense outer growth to stimulate inner budding.

Watering

Water thoroughly when the top centimeter of substrate dries — Carmona requires consistent moisture but suffers in waterlogged conditions. Never allow the root ball to dry completely as this triggers rapid leaf drop and shoot dieback from which recovery can take weeks. In centrally heated rooms, daily watering may be necessary as pots dry quickly in low humidity. Stand pots on humidity trays filled with wet gravel to raise local humidity around the canopy. Foliage misting in the mornings benefits the tree but avoid misting in cold conditions as wet foliage in cool air invites fungal issues.

Soil & Repotting

Repot every two to three years in late spring once stable warm temperatures are established — never repot in winter or when temperatures fluctuate. A free-draining mix of 50% akadama, 30% pumice, and 20% composted bark or coir provides moisture retention with adequate drainage. Root reduction of up to one-third is tolerated in warm stable conditions. After repotting, keep the tree in the warmest, most humid spot available and reduce watering frequency for two weeks while new root growth establishes. Never repot and move the tree simultaneously.

Group Soil Recipes

Broadleaf evergreen substrate balances moisture retention with drainage: 50% akadama, 25% pumice, 15% lava rock, 10% composted bark. Olive bonsai prefer very fast-draining, mineral-rich substrate with extra pumice and minimal organic matter. Boxwood tolerates standard mixes. Privet and holly are undemanding regarding soil composition. Repot every 2–3 years in spring. Camellia prefers acidic substrate similar to azalea, using kanuma instead of akadama. Mediterranean species like olive and myrtle benefit from a limestone chip addition for calcium.

Fertilizing

Feed with a balanced liquid fertilizer every two weeks from spring through autumn, and monthly through winter if the tree is kept in a warm room with good light. Carmona is a moderate feeder — consistent light feeding produces better results than infrequent heavy doses. A fertilizer with a slight phosphorus emphasis supports the continuous flowering habit. Reduce feeding by half in winter if growth has slowed. Withhold fertilizer for four weeks after repotting.

Light & Placement

Carmona requires bright light — a minimum of four to five hours of direct sunlight daily, either from a south-facing window or under grow lights with a minimum output of 5000 lux. Insufficient light is the most common cause of poor performance as an indoor bonsai: growth becomes etiolated, flowering ceases, and the tree becomes susceptible to pests. Direct summer sun through glass can cause leaf scorch — diffused light or light shade cloth outdoors in summer suits the species. Minimum temperature 15°C; optimal growing range 20-30°C. Never place near air conditioning vents or cold windows.

Seasonal Placement Guide

Spring: New growth flushes; begin feeding with balanced fertilizer; prune to maintain shape as new growth extends. Summer: Regular watering; olive and Mediterranean species tolerate heat and some drought; protect boxwood from sunburn. Autumn: Reduce feeding; camellia buds swell for winter bloom; prepare cold-sensitive species for winter protection. Winter: Protect subtropical species from frost; olive trees need cool but frost-free conditions; camellia blooms in late winter. Boxwood and holly tolerate moderate cold.

Seasonal Care

Spring: Increase watering and feeding as temperatures warm, repot if due, move outdoors once night temperatures exceed 15°C. Summer: Maximum light and warmth, frequent watering, monitor for whitefly weekly, enjoy flowering and fruiting. Autumn: Bring indoors before temperatures fall below 15°C, transition gradually over one week, maintain humidity. Winter: Bright window or grow lights essential, reduce feeding, maintain warmth, monitor for spider mites and whitefly in dry indoor air.

Group Seasonal Guide

Spring: New growth flushes; begin feeding with balanced fertilizer; prune to maintain shape as new growth extends. Summer: Regular watering; olive and Mediterranean species tolerate heat and some drought; protect boxwood from sunburn. Autumn: Reduce feeding; camellia buds swell for winter bloom; prepare cold-sensitive species for winter protection. Winter: Protect subtropical species from frost; olive trees need cool but frost-free conditions; camellia blooms in late winter. Boxwood and holly tolerate moderate cold.

Pests & Diseases

Whitefly (Trialeurodes vaporariorum and related species) is the defining pest problem of Carmona bonsai — adults and larvae colonize the undersides of leaves, sucking sap and excreting honeydew that promotes sooty mold. Treat with yellow sticky traps plus systemic imidacloprid soil drench; biological control with Encarsia formosa parasitic wasps is effective. Spider mites thrive in dry indoor conditions — regular misting and humidity trays reduce infestations; treat with miticide spray covering leaf undersides. Scale insects on branches are removed manually and treated with horticultural oil. Root rot from overwatering requires immediate substrate improvement.

Group Pest Guide

Olive moth larvae mine leaves and bore into fruit; apply appropriate insecticide. Boxwood blight causes dark leaf spots and rapid defoliation; fungicide treatment and removal of affected growth is essential. Boxwood leafminer creates blistered leaves; treat with systemic insecticide in spring. Scale insects affect most broadleaf evergreens; treat with horticultural oil. Holly leaf miner creates serpentine trails in leaves; systemic insecticide in spring is effective. Sooty mold from honeydew-producing pests is common; treat the underlying pest infestation.

Propagation

Semi-hardwood cuttings taken in summer root readily at 25-28°C with 0.3% IBA hormone and high humidity. Use 8-12 cm shoots with lower leaves removed, insert in perlite-coir mix, and maintain under a humidity dome for four to six weeks until rooting occurs. Air layering in summer on branches 1-2 cm diameter is highly reliable and produces new trees with established branch character within one growing season. Seed germinates readily at tropical temperatures but seedling development is slow and variable. Cuttings from selected bonsai specimens maintain the parent's leaf size and growth characteristics.

Group Propagation Guide

Olive propagates from semi-hardwood cuttings or by salvaging ancient olive wood with some living cambium. Boxwood cuttings root readily in summer within 6–8 weeks. Privet is extremely easy from cuttings taken at almost any time during the growing season. Holly propagates from semi-hardwood cuttings under mist; berried varieties require both male and female plants. Camellia is typically grafted for named cultivars or propagated from semi-hardwood cuttings in summer. Mediterranean species like myrtle root easily from cuttings.

Size Classification

Carmona is effective at all scales from shohin (15-25 cm) through medium bonsai (40-60 cm). The small leaf size (1-2 cm) maintains correct proportion even on very small trees. Shohin Carmona with developed trunks and established nebari are prized indoor bonsai. Large specimens over 60 cm with genuine trunk caliper become impressive statement pieces but require correspondingly larger indoor growing spaces to meet their light requirements.

Varieties & Cultivars

Carmona retusa 'Variegata' has creamy-white leaf margins and is occasionally offered by specialist dealers. Compact-growing clones selected for smaller leaf size are available in some bonsai nurseries in Southeast Asia and are superior to generic nursery stock for bonsai development. The related Carmona brevistyla has slightly larger leaves and is occasionally offered as Fukien tea. Species identity is often confused in the trade — inspect the characteristic white-dotted leaf surface to confirm genuine C. retusa.

Group Varieties

Buxus harlandii (Harland boxwood) is the premier bonsai boxwood with naturally small leaves. Olea europaea (olive) develops ancient-looking trunks and tolerates heavy styling. Ligustrum (privet) grows vigorously with small leaves. Ilex (holly) species offer dark glossy foliage and occasional berries; I. crenata has tiny leaves. Myrtus communis (common myrtle) has fragrant foliage and white flowers. Camellia sasanqua is more suited to bonsai than C. japonica due to smaller flowers and leaves. Serissa foetida (snow rose) has tiny leaves and flowers but is temperamental.

Buying Guide & Display

Avoid mass-market supermarket and hardware store Carmona bonsai — these are grown rapidly in warm greenhouses and placed in incorrect potting mixes, often with glued-on decorations. Purchase from specialist bonsai nurseries that can confirm the plant has been properly conditioned for indoor culture. Look for specimens with genuine trunk taper, visible bark character, compact well-ramified branching, and current healthy leaf growth. Ask how long the specimen has been indoors — trees recently moved from outdoor growing need an acclimatization period before purchase.

Troubleshooting

Sudden leaf drop without yellowing is almost always a response to cold exposure, drafts, or being moved — locate and eliminate the cause before new growth will stabilize. Yellow leaves with fine webbing on the undersides indicate spider mite infestation — treat immediately and raise humidity. Sticky honeydew residue on leaves and pot indicates whitefly or scale — inspect undersides of all leaves thoroughly. A tree that fails to flower despite adequate light likely needs higher phosphorus fertilization and potentially more direct sun. Mushy stem bases indicate root rot — remove from pot, cut away affected roots, dust with fungicide, and repot into fresh dry substrate.

Common Problems

Display & Exhibition

Carmona bonsai is displayed to maximum effect when flowering and fruiting simultaneously — a state achievable year-round under ideal conditions. A glazed oval pot in earth tones (brown, cream, or dark green) complements the dark foliage and red-to-black berries. At tropical and indoor bonsai exhibitions, Carmona with simultaneous flower and multi-stage fruit development represents the highest display achievement for the species. The white-spotted leaf surface adds subtle textural interest visible at close inspection range.

Group Display Guide

Broadleaf evergreen bonsai provide year-round display options. Olive bonsai are displayed to emphasize their ancient, gnarled trunks and silver-green foliage. Boxwood is showcased for its dense, refined pad structure. A Mediterranean-themed display with stone accents suits olive and myrtle. Camellia is displayed during its winter bloom season, often paired with a seasonal scroll. Glazed pots in subtle greens or blues complement the evergreen foliage. The display should emphasize the natural character of the species.