Coprosma, Mirror Plant: Planting, Cultivation

Botany

The Coprosma is a small evergreen bush from the Rubiaceae family, just like Gardenia. The Coprosma genus consists of 90 species native to Oceania, more specifically New Zealand, along with numerous hybrids recently introduced to the European horticultural market. The bush has a particularly dense, upright and compact habit. Within 4 or 5 years, it forms a bush reaching about 50 cm to 1.50 m in height depending on the variety. In its native habitat, this bush can grow up to 3 m tall.

Coprosma nitida, botanical plate circa 1840

The Coprosma stands out for its glossy, colourful and changing foliage that persists through winter, brightening the garden all year round. The flexible, ramified stems bear small opposite leaves, ovate to lanceolate, leathery, shiny on top and matte underneath. They are marked by a lighter midrib. Leaf colours vary by cultivar, ranging from soft green to chocolate brown touched with bright green or pink, through to red, bronze or purple. Some varieties display multicoloured foliage like the Coprosma ‘Evening Glow’. With each change of season, their colours evolve. Their beautiful hues are lighter in summer, darkening and turning purple under the effect of cold. The whole forms a sparkling bush that reflects light, hence its nickname “mirror plant”.

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

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

Main species and varieties

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Planting

Where to Plant Coprosma?

Originating from New Zealand, Coprosma retains a certain sensitivity to cold and a preference for mild climates. Not very hardy, it starts to suffer at -3 to -5°C (sometimes down to -8°C in well-drained soil) and prefers mild winters. Hybrid varieties often show greater resistance to diseases and cold. It can only be grown in the ground in coastal gardens spared from severe frosts. In regions with harsh winters, it should be grown in pots on patios or balconies during the warmer months before being moved to shelter for winter in a cool, bright, and minimally heated room.

Highly tolerant of salt spray and drought once established, Coprosma is an ideal plant for coastal gardens. It thrives in full sun or lightly shaded spots in the south of the country and prefers light, well-draining soils that are not too dry to moist and free from lime. It tolerates poor soils.

With its dense, colour-changing foliage depending on the variety, it can be planted in borders, rockeries, low hedges, or at the front of a sheltered flowering or mixed hedge. Its compact growth makes it perfectly suited to container cultivation.

Coprosma montana (© Forest and Kim Starr)

When to Plant Coprosma?

Coprosma is best planted in spring, from April to May, avoiding frost or drought periods.

How to Plant the Mirror Plant?

In the ground

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

• Dig a planting hole twice the width of the root ball
• Add a 10cm drainage layer (pumice or gravel) at the bottom if your soil is clay-heavy
• Mix garden soil with turf and some horticultural sand
• Plant without burying the collar
• Firm the soil and water
• Monitor watering for the first two years

Container cultivation

Choose compact varieties like ‘Mini Mac’.

• Place a generous drainage layer (gravel or clay pebbles) at the bottom of the pot
• Plant in a mix of leaf mould, heather soil, and river sand
• Water thoroughly and maintain regular watering
• Place the pot on a patio sheltered from scorching sun and strong winds

Maintenance, Pruning and Care

The Coprosma requires minimal care and maintenance. Ensure it does not lack water during its first few summers to help with establishment. Once well-established, it can go without watering in summer in most regions, except during prolonged droughts. Potted specimens have greater water needs; water once a week throughout the growing season.

In colder regions, when the first frosts arrive, remember to move pots indoors to a bright, frost-free room.

Pruning is not essential but involves cutting back dead stems, those damaged by winter frost or spent flowers between April and August. It helps maintain a neat, bushy, and compact shape while stimulating new shoot growth. Prune sparingly using pruning shears.

Coprosma repens ‘Marble Queen’ (© Cultivar 413)

Diseases and potential pests

The Coprosma is a hardy plant. It may occasionally suffer from scale insect attacks, particularly when grown in a greenhouse: spray rapeseed oil to suffocate the pests.

Propagation

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

• Take 8 to 10 cm stems
• Remove the lower leaves, keeping only those at the top
• Plant the cuttings in a bucket, in a moist mixture of river sand and compost
• Keep covered until rooting, then protect from frost all winter
• Transplant the cuttings into the ground or into pots in spring

Pair with

Coprosmas are perfect for adding a permanent splash of colour, more or less vibrant depending on the cultivar, to any planting scheme. With their glossy, ever-changing foliage, they play wonderfully with light, brightening up dull areas of the garden throughout the seasons. They are invaluable in coastal gardens.

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

Specimens with striking habits, such as ‘Fire Burst’, can be planted in a bed of compact bushes featuring green foliage (Lonicera nitida), golden hues (golden oregano, Chamaecyparis obtusa ‘Kamarachiba’, Berberis thunbergii ‘Aurea Nana’, Mexican orange blossom), or purple tones like those of Berberis.

They can be paired with any type of bush in low hedges. In autumn, their colourful foliage will harmonise beautifully with smoke bushes or Sacred Bamboo, Japanese maples and spindle trees in mahogany hues. They also pair effortlessly with other acidophilous plants such as Cercidiphyllum japonicum (Katsura tree).

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