Plant of the Month: February

Erica carnea Common name: winter heath Family: Ericaceae Vital statistics Height and spread: 30cm (12in) high 50cm (20in) wide Form: Small prostrate shrub Life span: 10 years Soil: Any well-drained soil; all Erica carnea cultivars are lime-tolerant Aspect: Full sun or partial shade Hardiness: Hardy throughout the British Isles

When you enter the Gardens your first view is looking out over Tarn Meadows where you are able to see some of the winter-flowering heaths planted amongst other Erica species and cultivars. Also planted here are Daboecia, Calluna and other plants including dwarf conifers, birches and Japanese maples all of which tumble over the rocks and provide interest throughout the year with flowers, foliage and stems.

The other main area to see Erica carnea cultivars is in the Trials and Collections Beds where there is a good reference collection planted.

Heaths

Erica is a large genus of over 700 species of evergreen shrubs ranging in habit from ground-hugging dwarf shrubs to small trees. They occur in equally diverse habitats from wet moorland to dry heathland in Europe, temperate Africa and Asia, with over 90 percent of ericas coming from the Cape Province of South Africa.

The name Erica comes from the Greek word ereike, meaning heather, which in turn comes from the word ereiko meaning to break, as an infusion made from the leaves was reputed to break bladder stones.

With few exceptions ericas are lime-hating and thrive best on sandy, acid soils. They will tolerate partial shade but will flower best in full sun. Combining different ericas within a planting means that it is possible to have a display of flowering heaths throughout the year.

One species of Erica is of economic importance, other than as a horticultural crop. The root of Erica arborea, tree heath, is used to make briar pipes as it is tough, porous, and nearly impervious to heat. It grows in the dry, rocky wastelands around the Mediterranean and for the finest quality pipes can often be 50 to 100 years old when harvested.

Erica carnea

The winter heath is one of the most widely grown dwarf shrubs in cultivation, forming dense hummocks and mats covered with rosy-red flowers throughout the winter. The epithet carnea describes the colour of the flowers, meaning as it does flesh-coloured.

Erica carnea is naturally found in coniferous woods and on stony slopes in central and eastern Europe, particularly the Alps, north west Italy and the north west Balkans. It was introduced into Britain by the Earl of Coventry in 1763, since when numerous cultivars have been raised.

Around 200 cultivars have been bred, with a range of foliage characteristics and flower colours. All tolerate a mildly alkaline soil and partial shade though they thrive best on a neutral, sandy soil in full sun.

The foliage is usually dark green comprising linear leaves less than 10mm (1/2in) long in whorls of four around the stem. The flowers are borne in a terminal inflorescence up to 10cm (4in) long with individual flowers about 5mm to 10mm, opening long from winter to mid-spring.

The classical use of Erica carnea cultivars is within plantings of other heaths and heathers (including Calluna and Daboecia) birches, dwarf rhododendrons and dwarf conifers. They can also be grown in containers for winter interest.

AGM

Several Erica carnea cultivars grown at Harlow Carr have received the Award of Garden Merit.

Erica carnea 'Adrienne Duncan' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Spreading dwarf evergreen shrub with dark purplish-green foliage and rosy-red flowers in leafy racemes'

Erica carnea 'Ann Sparkes' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen shrub forming a wide mat of golden-yellow foliage with racemes of bright purple flowers'

Erica carnea 'Foxhollow' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen heather with yellow-green young foliage, becoming reddish-yellow in winter. Flowers pale pink, in short racemes'

Erica carnea 'Loughrigg' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen heather forming a wide mat of dark foliage and racemes of rosy-purple flowers'

Erica carnea 'Myretoun Ruby' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen shrub with dark foliage and racemes of deep rose-pink flowers'

Erica carnea 'Pink Spangles' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Evergreen shrub of prostrate habit with mid-green foliage and racemes of light rose-pink flowers'

Erica carnea 'Praecox Rubra' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Low-growing, mat-forming dwarf evergreen shrub with dark green foliage and racemes of deep rose-pink flowers'

Erica carnea 'R B Cooke' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen shrub forming wide mats of mid-green foliage. Flowers clear pink, in racemes'

Erica carnea 'Springwood White' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Vigorous, prostrate evergreen shrub forming wide mats of mid-green foliage. Flowers white, in racemes'

Erica carnea 'Vivellii' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Prostrate evergreen shrub with dark green foliage tinged purple in winter. Flowers deep carmine-red'

Erica carnea 'Westwood Yellow' AGM
Given the Award of Garden Merit by RHS Floral Committee B and described thus: 'Compact prostrate evergreen shrub with golden yellow foliage and deep pink flowers'

Cultivation

Erica carnea will tolerate a mildly alkaline soil and some shade but they will grow better in an open, sunny position in a well-drained soil. The ideal times for planting heaths are in autumn and early spring, though container grown plants can be planted in winter if conditions allow.

Annual trimming will keep heaths in good shape, promote flowering and prolong the life of the plant. Every other spring, after flowering has finished, trim back the flower heads with shears. More vigorous cultivars can be pruned back harder, which will stop the centre of the plant going bare. Old plants that have become straggly are best replaced. For advice on pruning refer to the problem profile pruning evergreen shrubs.

Heaths do not generally suffer from pests and diseases except for phytophthora disease which can be lethal. Symptoms include silvering of the leaves followed by wilting of the stems and dieback.

Propagation

In mid or late summer non-flowering 3-4cm (1-11/2in) sideshoots can be used for semi-ripe cuttings. However, the simplest and most reliable method to produce new plants is to mound-layer in spring. A year later good roots will have formed and the new plants can be severed from the parent plant and moved to their final growing positions.

More information

Heathers (A-Z Plant Groups)

The RHS National Collection of Heathers (A-Z Plant Groups)

The Heather Society