Introduction

Thuja orientalis (now correctly Platycladus orientalis), the oriental arborvitae or Chinese thuja, differs from T. occidentalis in its vertically held foliage sprays and rounder, more symmetrical growth habit. The vertical spray orientation creates a distinctive texture unlike any other scale-foliage conifer, with the flat sprays standing edge-on to the viewer rather than lying horizontally. Native to China and widely cultivated across East Asia, the species carries deep cultural significance in Chinese penjing tradition and offers bonsai practitioners a unique foliage presentation achievable from no other commonly available species.

Platycladus orientalis (formerly Thuja orientalis) is native to northwestern China but has been cultivated so extensively across Asia that its natural range is uncertain. The tree reaches 15-20 m in cultivation. The key distinguishing feature is the vertical orientation of the flat foliage sprays — they stand upright rather than lying horizontally as in Thuja and Chamaecyparis. Bark is thin, reddish-brown, fibrous. Cones are distinctive — fleshy, blue-green when immature, with prominent hooked scales, unlike the thin-scaled cones of true Thuja. The species is more heat-tolerant than T. occidentalis but less cold-hardy.

History & Tradition

Oriental arborvitae has deep roots in Chinese penjing tradition, where it is one of the classic species alongside Pinus parviflora and Podocarpus. Temple specimens in China are centuries old and represent the living connection between Chinese culture and its native flora. The species symbolizes longevity and resilience in Chinese tradition. In Western bonsai, it is less commonly used than T. occidentalis but valued for its unique vertical spray texture.

About Other Conifers Bonsai

Beyond juniper and pine, the conifer world offers distinctive bonsai species with unique characteristics. Cryptomeria japonica (Japanese cedar) develops striking reddish bark and feathery foliage that bronzes beautifully in winter. Hinoki cypress (Chamaecyparis obtusa) has fan-like foliage sprays that create elegant layered silhouettes. Spruce, larch, and yew each bring different textures and growth habits to bonsai cultivation. Taxus (yew) is exceptional for its tolerance of heavy pruning and ability to regenerate from bare wood. Larch (Larix) stands unique among conifers as a deciduous species, dropping golden needles in autumn. These conifers generally prefer full sun, cool roots, and protection from extreme summer heat.

Botanical Profile

Platycladus orientalis (L.) Franco is now placed in its own monotypic genus Platycladus, separated from Thuja based on cone morphology, seed characteristics, and molecular evidence. Family Cupressaceae. Chromosome number 2n=22. The vertically oriented spray is the primary visual distinction from Thuja. The fleshy cone scales with hooked tips are diagnostic. The species is adapted to drier, warmer conditions than T. occidentalis.

Bonsai Styles

Informal upright is the most common style. The vertically oriented sprays create a unique texture when styled into pads — the foliage has a ruffled, vertical quality unlike the flat pads of horizontally oriented species. The naturally symmetrical, rounded growth suits formal compositions. Literati works on slender collected material. The species has a long tradition in Chinese penjing where it is styled in both naturalistic and stylized forms. Group plantings create unusual textural compositions.

Group Style Guide

Formal upright (chokkan) is the classic style for cryptomeria, reflecting their naturally columnar growth habit. Hinoki cypress suits informal upright and literati styles, with fan-like foliage creating layered silhouettes. Larch excels in forest plantings (yose-ue), their golden autumn color creating stunning group compositions. Yew tolerates virtually any style due to its ability to regenerate from bare wood. Spruce works well in formal and informal upright styles, with naturally tiered branch structure. Cedar (Cedrus) suits powerful informal upright and slanting styles with broad, horizontal branch pads.

Trunk & Nebari

Trunk development is moderate. The thin, fibrous bark adds texture at relatively small diameters. Old temple specimens in China develop massive, twisted trunks with impressive bark character. Surface roots develop through annual root combing. Ground-growing builds trunk diameter over four to six years.

Deadwood Techniques

Similar deadwood characteristics to T. occidentalis. The fibrous wood creates moderate deadwood with lime sulfur treatment. Old Chinese penjing specimens feature carved and sculpted deadwood — a tradition distinct from the Japanese approach. Jin and shari techniques follow standard practice.

Wiring & Shaping

Wire in autumn through early spring. The vertically oriented sprays require different handling than horizontal-spray species — the pads have a vertical rather than horizontal plane. Young wood is flexible. Aluminum wire for most work. The species responds well to wiring and holds positions once set.

Pruning & Pinching

Pinch extending spray tips with fingers, not scissors. The species tolerates heavy pruning and back-buds readily on old wood. Thin interior dead growth regularly. The vertical spray orientation means pads build differently from horizontal-spray species — work with the natural vertical tendency rather than forcing horizontal orientation.

Watering

More drought-tolerant than T. occidentalis. Water when the top 1.5 cm of substrate dries. Good drainage is important. The species tolerates drier conditions than most scale-foliage conifers. Reduce watering in winter.

Soil & Repotting

Repot every two to three years. Standard well-drained bonsai mix. Tolerates alkaline conditions. Root reduction up to one-third. Repot in early spring.

Group Soil Recipes

Cryptomeria and hinoki cypress use standard conifer mix: 40% akadama, 30% pumice, 30% lava rock. Larch prefers a slightly more moisture-retentive mix with 50% akadama, as they grow naturally in wetter conditions. Yew tolerates a wide range of substrates including mixes with up to 20% organic matter. Spruce prefers very well-draining, cool-root conditions with extra pumice. Repotting intervals vary: 2–3 years for vigorous species like cryptomeria, 3–5 years for slower-growing yew. All conifers benefit from mycorrhizal inoculant.

Fertilizing

Feed moderately with balanced organic fertilizer from spring through early autumn. The species is not demanding and responds well to moderate nutrition. Avoid excessive nitrogen.

Light & Placement

Full sun essential — more sun-loving than T. occidentalis. Hardy to USDA zone 6 — less cold-tolerant than T. occidentalis. Winter protection is needed in zones colder than 6. Tolerates heat better than most scale-foliage conifers.

Seasonal Placement Guide

Spring: Resume regular feeding; repot if needed as buds extend; pinch new growth on cryptomeria and cypress. Summer: Full sun for most species; larch needs protection from extreme heat; maintain consistent moisture. Autumn: Larch turns golden before needle drop; cryptomeria may bronze slightly; reduce feeding. Winter: Most are cold-hardy but protect container roots; yew tolerates the most cold; cryptomeria bronzing intensifies in cold. Larch is fully deciduous and requires cold winter dormancy.

Seasonal Care

Spring: Resume feeding, repot if due, pinch growth. Summer: Full sun, moderate watering. Autumn: Reduce feeding, wire branches. Winter: Protect from hard freezing in cold climates.

Group Seasonal Guide

Spring: Resume regular feeding; repot if needed as buds extend; pinch new growth on cryptomeria and cypress. Summer: Full sun for most species; larch needs protection from extreme heat; maintain consistent moisture. Autumn: Larch turns golden before needle drop; cryptomeria may bronze slightly; reduce feeding. Winter: Most are cold-hardy but protect container roots; yew tolerates the most cold; cryptomeria bronzing intensifies in cold. Larch is fully deciduous and requires cold winter dormancy.

Pests & Diseases

Similar pest profile to T. occidentalis. Spider mites, bagworms, scale insects. Juniper blight (Kabatina) occasionally affects the foliage. The species is generally pest-resistant. Less susceptible to winter damage than T. occidentalis in appropriate hardiness zones.

Group Pest Guide

Cryptomeria suffers from red spider mite in hot, dry conditions; maintain humidity and treat with miticide. Cypress bark beetle attacks stressed hinoki cypress; maintain tree vigor. Larch casebearer moth larvae mine needles; treat with systemic insecticide in spring. Yew scale appears as tiny brown bumps; treat with horticultural oil. Spruce gall adelgid creates pineapple-shaped galls on branch tips; prune and destroy affected growth. Needle blight fungi affect various conifers in wet conditions; improve air circulation and apply copper-based fungicide.

Propagation

Semi-hardwood cuttings root readily. Air layering succeeds within one growing season. Seed germinates after brief stratification. Named cultivars propagated vegetatively. Widely available as nursery stock.

Group Propagation Guide

Cryptomeria roots well from semi-hardwood cuttings taken in late summer; rooting hormone improves success rate. Hinoki cypress cuttings root under mist propagation within 8–12 weeks. Larch is best grown from seed, as cuttings root poorly; seed requires brief cold stratification. Yew roots readily from cuttings taken in autumn; this is one of the easiest conifers to propagate. Spruce is best from seed or grafting; cuttings root with difficulty. Cedar (Cedrus) propagates from seed or grafting. Collected specimens (yamadori) of conifer species often provide the fastest route to impressive bonsai material.

Size Classification

Effective from shohin to large. The small scale foliage maintains proportion at all sizes. The vertical spray orientation is visible and distinctive even at small scale. Medium specimens (30-50 cm) are the most common.

Varieties & Cultivars

'Aurea Nana' is a compact golden form popular in bonsai. 'Rosedalis' is extremely dwarf with soft juvenile foliage. 'Elegantissima' has golden-yellow foliage. 'Sieboldii' is a compact rounded form. 'Blue Cone' has blue-green foliage with a conical habit. Compact golden cultivars are particularly popular as bonsai subjects.

Group Varieties

Cryptomeria japonica (Japanese cedar, Sugi) has feathery foliage that bronzes in winter. Chamaecyparis obtusa (Hinoki cypress) has distinctive fan-like foliage sprays. Larix (larch) species are deciduous conifers with golden autumn color; L. kaempferi is the Japanese species. Taxus (yew) tolerates extreme pruning and shading. Picea (spruce) offers short-needled species like P. glehnii. Cedrus (cedar) has distinctive needle clusters on short spurs. Podocarpus has long, flat leaves and subtropical character. Tsuga (hemlock) has fine, small needles ideal for bonsai scale.

Buying Guide & Display

Nursery stock is widely available, especially golden cultivars. Select specimens with visible trunk structure and healthy foliage. Old temple or garden specimens in China are prized penjing material but are not available for export. For Western practitioners, nursery stock and garden-center cultivars provide the standard starting material. Verify cold hardiness for your zone.

Troubleshooting

Browning interior foliage is normal shade response — thin outer growth. Cold damage in zones below 6 shows as browning and dieback — improve winter protection. Golden cultivars reverting to green need more sun exposure. The species is less cold-hardy than often assumed — protect from temperatures below -15°C.

Common Problems

Display & Exhibition

Display in simple unglazed pots. The vertical spray texture is best appreciated from close range. Golden cultivars are particularly striking in exhibition. Position to show the spray orientation from the primary viewing angle. The species communicates Chinese cultural tradition when displayed in penjing style.

Group Display Guide

Other conifer bonsai follow display conventions similar to pine and juniper. Cryptomeria benefits from display angles showing the tapered trunk and layered branch structure. Hinoki cypress is displayed to showcase its fan-like foliage sprays. Larch forest plantings are displayed in autumn when golden needles create a miniature woodland scene. Yew bonsai are displayed to emphasize their dense, dark foliage and reddish bark. Formal dark stands suit most conifer species. A simple suiseki or companion grass anchors the composition.