Chamaecyparis, False cypress: planting, pruning and caring for

Description and botany

Genus Chamaecyparis comprises around six species, the boundary with Cupressus not always clear. For example, transfer of Chamaecyparis nootkatensis to Cupressus has been discussed. Both genera were even conflated in 19th century. They are often very large trees with highly scented wood and foliage. European settlers who first encountered these conifers called them ‘cedar’ because of wood scent. Several morphological criteria nevertheless allow differentiation. Persistent shoots of Chamaecyparis are flattened as in Thuja, whereas those of Cupressus are cylindrical. The latter have a straight leading shoot while Chamaecyparis have a flexible, curved leading shoot. Globose cones are smaller than in Cupressus.

Chamaecyparis occupy cool, humid northern regions of North America and East Asia (Japan, Taiwan) where they typically mix with other conifers in shaded, moist forests. Chen-mu or Sacred Tree (Chamaecyparis formosensis), longevity over 2,000 years, ranks among tallest trees in Taiwan with heights of 55–60 m and trunks up to 7 m wide, though it rarely exceeds 15 m in cultivation. Chamaecyparis lawsoniana from North America can also reach 60 m alongside Douglas fir and live to 600 years. Chamaecyparis nootkatensis, Nootka cypress, also called “yellow cedar” for wood colour, found along Pacific coast to Canada, reaches 36 m like its Japanese cousin Hinoki (C. obtusa), a slow-growing species with some specimens reaching 50 m. Sawara (C. pisifera) attains 45 m in Japan.

Chamaecyparis obtusa – botanical illustration by P.F. von Siebold and J.G. Zuccarini

Foliage made of scales in four ranks, more or less applied against the twig, is aromatic, with parsley scent in lawsoniana, cedar in obtusa, resinous in pisifera, resin described as unpleasant in nootkatensis… There are cultivars that retain juvenile foliage in form of short needles such as Japanese Hinoki ‘Wissel’ or Chamaecyparis thyoides Blue Rock. While C. lawsoniana shows bluish-green or dark matt green colouring, paler beneath, C. obtusa displays a very bright intense green on rounded twigs of beautiful texture and C. pisifera ‘Boulevard’ has feathery, silvery-green foliage. Numerous cultivars of genus offer very wide range of colours, textures and habits.

Bark often reddish, fibrous, forming long vertical strips.

Male and female flowering occur on same plant. Tiny male cones, greenish to yellowish, appear at twig tips and release pollen in March or April when female flowers develop at ends of other twigs.

Globose cones are strobili, sometimes fleshy, less hard and smaller (about 1 cm) than in Cupressus. Scales, 4 to 10 depending on species, bear small point on top, a fold in lawsoniana. They ripen in autumn when scales open to release winged seeds but often persist long on tree. Seeds are released earlier than in Cupressus.

Wood of false cypresses is fine-grained and durable, much prized by Japanese for coffins, temples, lacquered furniture and prestigious houses. After heavy exploitation of Hinoki (C. obtusa), they imported Lawson cypress wood from United States, contributing to decline of populations already badly affected by Phytophthora. Strict regulations now require cleaning tyres and boots when entering those native forests.

Chamaecyparis lawsoniana: scale foliage and globose cones

Main varieties of Chamaecyparis

Dwarf varieties

Medium-growing varieties

Chamaecyparis obtusa Teddy Bear - Hinoki Cypress

Small conifer with appearance of a large fern, bearing fine, dense foliage of a clear, quite intense green. Quite uncommon, its twisted silhouette inserts with elegance into borders, stands out as an isolated specimen, enlivens rockeries and adapts well to container culture. A curiosity to discover, easy to to grow in ordinary, fresh but well-drained soil, in sun or partial shade.

• Height at maturity 1 m

See the full description

Chamaecyparis thyoides Blue Rock

Recently discovered rare dwarf conifer species, with sumptuous foliage forming a compact ball with fine texture, initially blue-green, taking on violet to purple hues in winter. It grows very slowly, not exceeding 1.50 m in any direction at ripeness. Perfect for rockeries, small spaces or container culture, in sunny or partially shaded exposure, in soil remaining fresh, light and well drained, humus-bearing and rather acidic.

• Height at maturity 1,50 m

See the full description

Chamaecyparis obtusa Kamarachiba - Hinoki Cypress

Dwarf variety with a slightly loose rounded habit, somewhat hirsute and slightly flared. Its flat, lemon-yellow branches edged with cream fall gracefully in a charmingly calculated disorder, turning to coppery-bronze in winter. Will enliven small spaces, borders, rockeries or a container all year round. Prefers sunny or partially shaded exposure, fertile soil, rather fresh but well drained, not too calcareous.

• Height at maturity 1,25 m

See the full description

Chamaecyparis lawsoniana Green Globe - Lawson Cypress

Miniature bush forming a bright green ball with very dense foliage in youth that becomes more tousled with age. Not exceeding 50 cm at adulthood, it grows slowly and is particularly suited to permanent decoration of rockeries and containers. Appreciates sun and fresh, fertile soil, neutral to acidic.

• Height at maturity 50 cm

See the full description

Chamaecyparis pisifera Boulevard - Sawara Cypress

Remarkable variety for its soft fan-like blue-green foliage whose silvery highlights catch light beautifully, as if bush were in perpetual motion. Built in a slightly blurred cone, it acquires faint purplish tones under cold. This slow-growing conifer prefers sunny or partially shaded exposure, rather fresh but light and well-drained soil, humus-bearing.

• Height at maturity 2,50 m

See the full description

Chamaecyparis lawsoniana Yellow Spire - Lawson Cypress

Rockery conifer forming a somewhat lanky bush with a very narrow conical habit and a striking silhouette. Its curiously twisted feathery shoots are covered in spring with very bright yellowish-green young foliage, becoming blue-green with age. Not exceeding 1.40 m in height at adulthood, it grows slowly and is especially suited to permanent decoration of small spaces, rockeries and containers. Appreciates sun and fresh, fertile soil, slightly calcareous, neutral or slightly acidic.

• Height at maturity 2,75 m

See the full description

Chamaecyparis obtusa Aurea - Hinoki Cypress

Majestic Japanese conifer displaying a dense, rounded conical silhouette, adorned with twisted golden-yellow shoots in spring then light green. Thrives in full sun, in fresh, deep, well-drained soil.

• Height at maturity 9 m

See the full description

Chamaecyparis pisifera Filifera - Sawara Cypress

Broad, dense bush, later becoming pyramidal, with supple, slightly trailing foliage, bright to dark green. Its dishevelled aspect gives it a rather charming languid air. Perfect for rockeries and small spaces in sunny or partially shaded exposure, in rather fresh but light and well-drained soil, neutral or acidic.

• Height at maturity 5,50 m

See the full description

Chamaecyparis obtusa Snowflake - Hinoki Cypress

With fern-like foliage splashed with bright spots, it rivals flowering shrubs and will become a magnificent specimen planted alone in a small space or in a pot. Young spring foliage very compact, grey-green, randomly splashed with light, leaf tips variegated in cream-white or even grey turning to shadow green in summer. For ordinary soil, fresh but well drained, in sun or partial shade.

• Height at maturity 1,80 m

See the full description

Planting

Where to plant Chamaecyparis?

Chamaecyparis are not demanding about soil type, provided it is deep, cool and well-drained. They prefer cool conditions, not too sunny, in partial shade. In general, avoid climates that are too dry and soils that are poorly drained.

These conifers will also tolerate poor soil with moderate growth and reduced vigour, which is not necessarily a bad thing if wishing to keep specimens small. Some cultivars are more sensitive than others such as C. pisifera Boulevard or C. thyoides Blue Rock which both dislike calcareous soils, as well as excessive sun for the former and wind for the latter; C. lawsoniana Pottenii browns under drying winds or harsh winters… Chamaecyparis lawsoniana Ellwoodii with its grey-blue foliage, darker in winter, tolerates shade well.

Beware of waterlogged soils in winter which may promote development of Phytophthora cinnamomi if the fungus is present in the soil, because the species lawsoniana is very sensitive to it.

When to plant?

Prefer planting in autumn (October–November) to establish Chamaecyparis, or in February–March.

How to plant?

This plant is generally very easy to grow.

To create a clipped Chamaecyparis hedge, space young plants 80 to 100 cm apart and up to 2 m apart if used as a windbreak left in natural habit.

• Dip the pot in a bucket of water to soak it well.
• Dig a wide hole at least three times wider than the rootball because roots remain fairly superficial and spread widely.
• Add a few handfuls of sand and gravel to ensure good drainage around the roots. In heavy soil, opt for planting on a mound or within a rockery.
• Apply a dose of horn meal if soil is sandy.
• Place the plant in the planting hole.
• Replace the soil and firm lightly.
• Water and mulch.

In a pot, use a light humus-bearing soil or mix ¾ garden soil with ¼ pumice and ¼ compost. Choose specimens with slow growth such as Chamaecyparis obtusa Pygmaea or pisifera Boulevard.

Chamaecyparis obtusa ‘Nana Gracilis’

Care and pruning

Potted young plants require regular watering, especially in hot sun. Water young plants correctly during first 2-3 years.

Main pests and diseases of Chamaecyparis

Chamaecyparis is generally a bush that causes no maintenance problems when soil is healthy and it does not undergo long periods of drought. However use in single-species hedging sometimes leads to rapid contagion such as more or less severe twig dieback, which can be caused by:

• fungal browning which appears during wet springs on lower branches. Apply a fungicidal treatment every 15 days, using a copper-based product or horsetail decoction, or cut and burn affected twigs.
• Phytophtora to which Chamaecyparis is very susceptible, causing progressive desiccation of whole plant due to necrosis of collar tissues and roots under bark. Uproot and burn affected specimens and plant non-susceptible species.
• cortical canker which particularly affects Leyland cypress (x Cupressocyparis leylandii), a hybrid between Cupressus and Chamaecyparis. It causes bark cracking and resin exudations accompanied by black pustules. Cut and burn affected branches, dress wounds with mastic. Uproot if trunk is affected.
• root rot (Armillaria), favoured by heavy, wet soils, which causes sudden desiccation of plant accompanied by strong fungal odour. Uproot and leave planting hole open to air for one season. Replace soil.
• colonies of aphids (apply an insecticidal treatment quickly such as soap or fern manure),
• juniper buprestid which bores galleries in wood and causes browning in summer. Only solution is to cut and burn swollen twigs.

Pruning Chamaecyparis

These bushes or trees do not respond well to pruning, so prefer to use them in free habit when forming hedges. Always make very light pruning cuts, carried out in August if necessary, always retaining foliage.

Multiplication

Simplest way to multiply plants is to propagate a large number of semi-woody twigs in August–September because success is not guaranteed.

Propagation by cuttings

Prepare a box by filling it with a mix of half turf and half sand or work nursery soil.

• Take 10 cm-long shoots by pulling on them to retain a flap of bark.
• Remove branching near base of shoot.
• Insert these to one-third of their length, taking care that they do not touch.
• Firm down gently all around to remove air pockets and ensure good contact between growing medium and cutting.
• Place a cold frame over them and a shade cloth until spring.
• Separate the cuttings, pot up or plant out in nursery ground for 1–2 years, or plant directly in final position if soil is favourable

  → Discover our tutorial : How to take cuttings from conifers?

Uses and companion plants

Use Chamaecyparis for their singularity as isolated specimens in middle of a short grass meadow or as background for a flowering border such as Chamaecyparis obtusa ‘Nana Gracilis’ with an erect, mounding habit reaching 2 m at maturity, which unfolds clouds of shell-shaped dark green foliage. Some form a perfect cone such as lawsoniana Columnaris while others form a curtain 6 to 8 m in diameter and 10–15 m high such as C. nootkatensis Glauca.

An idea for a combination: Chamaecyparis thyoïdes ‘Rubicon’ (or ‘Blue Rock’ or other) on a luminous tapetum of heather Erica darleyensis ‘Eva Gold’, a few clumps of Festuca glauca and a few mounds of Berberis thunbergii ‘Atropurpurea Nana’

Smaller Chamaecyparis, thanks to slow growth, make perfect candidates to ornament a rockery, a small garden or a terrace in pots. With naturally sculptural silhouettes that do not require pruning, they offer striking graphic qualities suited to contemporary gardens as well as naturalistic gardens. They combine well with other dwarf conifers such as thujas, junipers, cryptomerias or with bushes with flowers for acid soils and cool areas such as azaleas, andromedas, heathers or camellias. They can also be trained into cloud forms or grown as bonsai such as the obtusa ‘Aurea’ whose masses of golden foliage contrast nicely with dark colour of trunk.