Coprosma, mirror plant: planting, cultivation

Botany

The Coprosma is a small evergreen bush from the Rubiaceae family, just like Gardenia. The genus Coprosma comprises 90 species native to Oceania, particularly New Zealand, and many hybrids that have recently entered the European horticultural market. The bush has a particularly bushy, upright, and compact habit. Within 4 to 5 years, it forms a bush reaching about 50 cm to approximately 1.50 m in height, depending on the varieties. In its native environment, this bush can grow up to 3 m tall.

Coprosma nitida, botanical plate circa 1840

The Coprosma is distinguished by its beautiful glossy foliage, with varied and changing colours that persist in winter, brightening the garden throughout the year. The flexible, ramified stems bear small opposite leaves, ovate to lanceolate, leathery, shiny on the upper side, and matte on the underside. They are marked by a lighter midrib. The leaf colours vary according to the cultivars, ranging from light green to chocolate brown touched with bright green or pink, as well as red, bronze, or purple. Some varieties display multicoloured foliage, such as the Coprosma ‘Evening Glow’. With each change of season, their colours evolve. Their beautiful attire is lighter in summer, darkening and turning purple with the cold. The overall effect is a sparkling bush that reflects the light, hence its nickname “mirror plant.”

The summer flowering is insignificant. From August to September, it takes the form of clusters composed of small tubular white-green flowers with prominent stamens. The Coprosma is a dioecious plant, meaning that fruiting only occurs if male and female plants are grown side by side. If this is the case, the flowers are then followed by globe-shaped berries of vermilion orange that delight birds. Very decorative, these scarlet drupes harmonise with the often purple-tinged foliage in autumn.

Coprosma kirkii ‘Variegata’, Coprosma ‘Rainbow Sunrise’, and to the right fruits of Coprosma brunnea

Main species and varieties

Coprosma Mini Mac

An adorable dwarf version with extremely glossy foliage. Perfect in a pot on the terrace or balcony.

• Flowering time September, October
• Height at maturity 50 cm

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Coprosma repens Fire Burst

A particularly vibrant variety, decorative all year round. In the ground, it is a perfect bush for coastal gardens.

• Flowering time September, October
• Height at maturity 1,50 m

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Coprosma Evening Glow

A lovely variegated foliage that changes with the seasons. Very ornamental in a pot on the terrace or balcony.

• Flowering time September, October
• Height at maturity 1 m

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Coprosma robusta Pina colada

Its flamboyant and tangy colour enlivens the garden or terrace in all seasons.

• Flowering time September, October
• Height at maturity 1,20 m

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Coprosma Pacific Dawn

A small evergreen bush with very decorative foliage, all in shades! It forms a sparkling and multicoloured bush that is truly stunning.

• Flowering time September, October
• Height at maturity 1,50 m

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Coprosma Pacific Night

A dark and sparkling foliage that is extremely glossy. It boasts a bright green dress, taking on purplish hues in spring at the first signs of cold.

• Flowering time September, October
• Height at maturity 1,50 m

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Coprosma Pacific Sunset

This tender bush will be magnificent in a pot on the terrace or balcony!

• Flowering time September, October
• Height at maturity 1,50 m

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Young plantation

Where to Plant Coprosma?

From its New Zealand origins, Coprosma has retained a certain sensitivity and a preference for mild climates. Not very hardy, it begins to suffer at temperatures of -3 or -5 °C (sometimes down to -8 °C at the extremes, in very well-drained soil), and prefers mild winters. Hybrids often show greater resistance to diseases as well as cold. It is only cultivated in open ground in coastal gardens spared from severe frosts. In regions with harsh winters, it should be grown in a pot on the terrace or balcony throughout the growing season before being stored away for winter in a cool, bright room that is minimally heated or unheated.

Very tolerant of sea spray and drought once well established, Coprosma is an ideal plant for coastal gardens. It enjoys very sunny or slightly shaded exposures in the southern parts of our country and thrives in light, very well-drained soils that are not too dry to fresh and free of lime. It tolerates poor soils.

With its dense foliage in changing colours, depending on the varieties, it can be planted as a border, in rockeries, as a low hedge, or at the front of a flowering or mixed hedge that is well protected. Its small growth habit is perfectly suited for pot cultivation.

Coprosma montana (© Forest and Kim Starr)

When to Plant Coprosma?

Coprosma planting is preferably done in spring, from April to May, outside of frost or drought periods.

How to Plant the Mirror Plant?

In Open Ground

Space the plants 1 m to 1.50 m apart for the larger varieties and 0.50 to 0.60 m for dwarf Coprosmas. Drainage must be perfect. In water-retaining soil, prefer planting on a mound.

• Dig a planting hole twice the diameter of the root ball
• Add a 10 cm drainage layer (pumice or gravel) at the bottom of the hole if your soil is clayey
• Mix garden soil with peat and a bit of garden sand
• Plant without burying the collar
• Firm the soil and water
• Monitor water supply for the first two years

Pot Cultivation

Choose compact varieties like ‘Mini Mac’.

• Spread a good layer of drainage (gravel or clay balls) at the bottom of the container
• Plant in a mixture of leaf compost, heather soil, and river sand
• Water, then provide regular water supply
• Place your pot on a terrace sheltered from scorching sun and strong winds

Maintenance, pruning and care

Coprosma requires little care and maintenance. Ensure it does not lack water during its first summers to aid its establishment. Once well-established, it can do without watering in summer in most of our regions, except in cases of prolonged drought. Potted specimens have greater water needs; water once a week throughout the growing season.

In cold regions, when the first cold weather arrives, consider bringing the pots indoors to a bright, frost-free room.

Pruning is not essential; it involves cutting back dead stems, damaged by winter cold or faded flowers between April and August. This helps maintain a nice bushy and compact shape and stimulates the production of new shoots. Prune with a pruning shear, always sparingly.

Coprosma repens ‘Marble Queen’ (© Cultivar 413)

Diseases and potential pests

Coprosma is quite resilient. It can sometimes suffer from scale insect attacks, especially if grown in a greenhouse: spray with rapeseed oil to suffocate the unwanted pests.

Multiplication

You can propagate Coprosma by semi-woody stem cuttings in summer.

• Take cuttings of 8 to 10 cm
• Remove the lower leaves, leaving only the upper ones
• Plant the cuttings in a bucket, in a mixture kept moist of river sand and potting soil
• Keep in a humid environment until rooting, then protect from frost throughout winter
• Transplant the cuttings into the ground or pots in spring

Associate

Coprosmas are perfect for adding a beautiful, permanent splash of colour, more or less flashy depending on the cultivars, to any composition. With their shiny and changing foliage, they play wonderfully with light, awakening the somewhat dull areas of the garden throughout the seasons. They are invaluable in a seaside garden.

At the edge of a lush flowerbed, the shorter varieties will find their place alongside a mix of brightly coloured perennials: Rudbeckia, Echinacea, Salvia greggii ‘Mirage Burgundy’, phormiums, daylilies or dahlias, all punctuated with stipas for a delicate and wild touch. The small blue flowers of the sages will be good companions.

Remarkable specimens with their habit, such as ‘Fire Burst’, can be installed in a flowerbed of compact bushes made up of plants with green foliage (Lonicera nitida), golden (golden oregano, Chamaecyparis obtusa ‘Kamarachiba’, Berberis thunbergii ‘Aurea Nana’, Mexican Orange Blossom), or purple like that of Berberis.

They can be combined in low hedges with any type of bushes. In autumn, their colourful foliage will harmonise beautifully with smokebushes or Sacred Bamboo, Japanese maples, and Euonymus with mahogany hues. They easily accompany other acidophilous plants such as Cercidiphyllum japonicum (the Caramel Tree).

Coprosma ‘First Burst’ (© Leonora Enking), Choisya ternata ‘White Dazzler’, Berberis thunbergii ‘Admiration cov’, and Chamaecyparis obtusa ‘Karamachiba’