nav-left cat-right
cat-right

Growing heathers and heaths

Easy-to-grow heathers bring year-round colour to gardens in almost any climate.

Easy-to-grow heathers bring year-round colour to gardens in almost any climate.

 

 

Heathers are incredible plants that offer real value for money. As a group they flower all year round and individually can be in bloom for several months, with few other plants able to rival the winter-flowering forms for sheer flower power at that time of the year. The flowers vary from the purest white, through pinks and reds of every shade to the deepest purple. Many have attractive foliage too offering bold splashes of gold, bronze, orange, red and even silver, which being evergreen, provides year-round interest.

When people mention heather, they are almost always talking about two different genera of plants: heaths and heathers. Although both belong to the Ericaceae family, they are botanically different and are divided into the Calluna genus and the Erica genus. There are is also Daboecia which is a tiny group of only two species. For practical purposes, however, they are nearly identical, sharing colour, form, and growth habits. They are all evergreen, well-mannered, and low-maintenance plants that thrive in similar conditions of sunlight, water, and soil.

Calluna comes from the Greek word kallunein, meaning to cleanse, probably because the twigs were used to make brooms. Callunas have just a single species, C. vulgaris, but over 800 cultivated forms are in existence.

Erica is from the Greek work ereiko meaning ‘to break’. Possibly because the stems break easily and possibly because of the medieval belief that it could be used medicinally to dissolve gall stones.

Species can be identified fairly easily on close inspection because callunas have tiny overlapping scale-like leaves which are quite distinct from the needle-like leaves of ericas. Heathers range from the carpet-forming, 5cm high Calluna vulgaris varieties such as ‘White Lawn’ to the immense tree heathers, Erica arborea, which can reach more than 6m in height. Then there are the almost infinite variations in leaf colour from buttery yellows and bright oranges through all manner of greens to bluish silvers and lavender greys. On their own, each heather is a fairly average, if useful plant, but the sight of a carpet of all different heathers is truly spectacular, probably unbeatable.

All true heathers are cultivars of just one species, Calluna vulgaris (which some botanists erroneously classify as Erica vulgaris), and there are easily more than 500 varieties available. Most are summer-blooming, ranging from white to rose to deep purple, and their foliage is green to fire orange; their leaves are small and scalelike. Most form low-growing mounds or spreading mats. For the heather lover in the North, these are the plants of choice, as opposed to the true heaths, which offer more colours but are generally less hardy. These low, mounding shrubs are the ling of Scotland, the famous heather of the Highlands.

erica-compwc-lores2The true heaths belong to the Erica genus and include more than 700 species and countless cultivars, such as winter heath (Erica carnea), bell heath (Erica cinerea), Darley Dale heath (Erica x darleyensis), Cornish heath (Erica vagans), and cross-leaved heath (Erica tetralix). Hardiness ranges widely; for instance, Erica carnea will bloom under snow, but many of the South African varieties, such as blood-red heath (Erica cruenta), are best left to southern hemisphere gardens. The true heaths offer an amazing range of foliage and bloom colour, well beyond the pinks of the heathers; they also come in taller shrub forms and even some small trees. With hundreds of species and cultivars the heaths provide a wide variety of colours and bloom times to fill your garden.

Other than heaths’ greater susceptibility to cold weather, the main difference between heaths and heathers is that heaths have needle-like leaves rather than flat leaves. The scale-like leaves of heather, in fact, feature tiny hairs, which give the foliage a greyish cast. Calluna cultivars also produce blooms where the corolla (or whorl of petals) is completely encased by the calyx (the usually green ‘leaves’ directly beneath a bloom); the Erica species and varieties feature prominent corollas and small calyxes, which often create a two-tone effect to the blooms. However, the bloom shapes are so nearly the same, that only a botanist or a true fanatic will know the difference.

Selecting plants by colour isn’t as simple as deciding you like pink blooms; selection by bloom colour is actually secondary to the foliage display. A heather’s evergreen foliage changes and intensifies in hue during cold weather. For example, Calluna vulgaris ‘Firefly’ has copper foliage in summer that changes to brick red in winter; Erica x watsonii ‘Dawn’ (a Watson’s heath) has red spring growth that turns to gold later in the year. It is this variability that makes heaths and heathers such arresting plants for the landscape. There are so many colours available that selecting plants can be intimidating, and people often make the process more complicated than needed.  The colours are so harmonious, however, that a homeowner should pay more attention to plant sizes and spacing. Selecting plants that will fill a designated space is easier to achieve than trying to work a plant of every bloom and foliage colour into the scheme.

Heathers vary in habit from upright to prostrate. The smallest are no more than a few centimetres tall, while the tree heath Erica arborea can reach a height of up to 6 m. The flowers are shaped like small urns or bells and range in colour from white through pink and lilac to crimson and deep purple. The foliage includes bright greens, yellows, oranges and dull reds.

Although some of the more spectacular heather gardens consist of large areas planted en masse, this factor should not discourage gardeners with less interest in heathers, or who have limited time or space available for gardening. The wide differences in sizes and forms of heathers permit exquisite use of these plants in small gardens. In fact, many prefer to see heathers planted as individual specimens or arranged in small groups. One of the challenges of heather gardening is to make the best use of almost unlimited plant options to match individual tastes and garden limitations.

Heathers need an open position in full sun and thrive in exposed gardens. Many make excellent groundcover plants. They are also splendid additions to beds and borders and useful container plants, particularly those that bloom in winter when few other container plants provide colour. Heathers are ideal for a low-maintenance garden because they require little care once established.

GROWING GUIDE

Heathers like an open position with plenty of sun – particularly those with coloured foliage. The soil also needs to be suitable. Unless you already know your soil’s pH, use a simple soil testing kit before making your heather selection. If the pH is above 7.5 choose from the lime-tolerant species, such as Erica carnea, E. x darleyensis and E. erigena varieties, but if it’s 6.5 or below you can choose from any type of heather. Heathers have shallow roots which means that they are excellent for growing in areas with thin soil. Although very drought tolerant once established, their shallow roots means they will have to be watered during dry spells during their first couple of growing seasons. Heathers do not need feeding. To get a quick groundcover of carpeting heathers, space plants about 30cm apart. To see heathers as distinct mounds, plant them at about twice this distance. Large heathers should be treated like shrubs and spaced according to their ultimate size.

Without good drainage, these plants just won’t grow. For clay soil (which provides neither the right pH nor proper drainage), build a raised bed with equal parts topsoil, sand, and composted bark or peat moss, which will create acidic soil that properly drains. For boggy soil (which may be the right pH but too wet), make a modest berm.

Shear newly purchased plants to encourage bushiness, and plant in spring or early autumn. Water twice a week for the first several months so the ground is moist but not soggy. This will encourage rapid, vigorous growth to get plants established. Apply a mulch of your choice, preferably an acidic one (such as pine straw, peat moss, or leaf mold). After two or three years, heathers and heaths are generally drought-tolerant and can take care of themselves.

Space the plants about as far apart as the plant’s mature width to allow air circulation, which is important for good foliage growth and colour but close enough so the plants will eventually mound together.

Allow for a minimum of six hours of sun a day for best foliage effect. The foliage will be best on the north side of the plant (in the southern hemisphere, south side in the northern hemisphere), especially for red varieties. Six or more hours of sun are also recommended with afternoon shade in hotter areas. Too much shade makes the plants leggy and dulls the brilliance of those that have colourful foliage. Avoid situating plants in areas that receive harsh winter winds; as evergreens, they suffer severe dehydration.

Heaths and heathers actually like poor soil. Giving annual doses of fertiliser is deadlier than not giving any at all. Fertilise once with rhododendron feed upon planting — then leave your plants alone. About the only work you need to do is give them a yearly shearing. This is best done in the spring before any buds have set or, for winter bloomers, after the flowers have faded. Calluna vulgaris should be cut back below the old flowers; the Erica spp. can be lightly pruned to encourage bushiness.

COMPANION PLANTS

In borders

A wonderful plant to mix with different heathers is Pieris japonica ‘Forest Flame’. Calluna vulgaris ‘Hammondii Aurefolia’ is a lovely heather with fresh, bright green leaves that contrast very well with the acid-green of the pieris. The boughs of dainty white pieris flowers are followed by the petite white flowers of the heather from August right through to October. Calluna vulgaris ‘Firefly’ with its brick-red foliage also works well, highlighting the young red leaves of the pieris and the light, fresh green of the other heather. Darker green heathers can be added, too and white spring-flowering heathers such as Erica carnea ‘Whitehall’ to draw together the pieris flowers. In the summer when the red leaves of the pieris have matured to green, Calluna vulgaris ‘Darkness’ with its dark pink flowers adds in a richness to the different greens of the leaves. In this way, really interesting and changing tapestry can be created easily.

Heathers are excellent plants for any very exposed position, on harsh, howling hillsides or by the seaside with its fierce, salty winds. The bright, bleeching sun of coastal gardens suits a combination of white, silver and blues with splash of vibrant colour for dramatic contrast. The pale blue flowers and silvery leaves of Lavandula ‘Miss Katherine’ , the spiky, steely-blue flowers of Eryngium ‘Bourgattii’ offset the big, rich-dark-blue flowerheads of Agapanthus ‘Bressingham Blue’ and their luscious green leaves. Calluna vulgaris ‘Kerstin’ with its unusual, lilac-grey foliage and dusky, rose-pink flowers is a perfect and elegant companion. Also use darker-leaved heathers, such as Erica carnea ‘Challenger’, with its deep, purple-plum flowers to add depth to the paler colours. The terracotta-leaved heathers work well here too. The combination of silvery grey, green and rust foliage is really striking in winter when there is very little other colour around. 

In rock gardens

There are some low-growing heathers that are perfect plants for a sunny rock garden. Planted in a patchwork they create a stunning effect. Erica carnea ‘Ann Sparkes’ is ideal, being a very slow-growing variety reaching 15cm tall and only spreading to 25cm across. It has a dazzling combination of orangey-yellow foliage with brighter bronze tips and rich magenta flowers produced in mid-spring. For autumn flowering Calluna vulgaris ‘Golden Carpet’ with its magenta flowers is a wonderful choice. The foliage is as equally stunning being a burnished yellow turning deep orange and red in the winter.

In containers

Heathers make excellent container plants because they can withstand drought — and pots are notorious for drying out! They also have very shallow roots systems, so they are best planted in wide container so the root system has as large an area as possible for getting water. It would also be easier to create an attractive swathe of several varieties. Winter-flowering heathers also make useful hanging basket subjects mixed with small flowered cyclamen, brightly variegated ivy and pansies.

PESTS AND DISEASES

As a rule heathers are fairly trouble free and are only attacked by fungal diseases, such as phytophthora, which are encouraged by warm wet conditions. The best thing to prevent this is to make sure the heathers are planted in well-drained soil — digging in well rotted compost or farmyard manure and grit will help if the conditions are not ideal. Otherwise, try spraying with a fungicide.

FOR SOUTH AFRICAN GARDENERS

The heaths described as Cape Heaths come from Southern Africa, south of the Limpopo river.

In this relatively small area, over 750 species can be found, which is thought to be the highest density for any genus of plant.

The weather pattern in Southern Africa varies widely, affording specialised habitats for many species. In some areas, where Erica is growing, it is not uncommon to have heavy falls of snow, but frosts are rarely recorded. Most endure long, dry summers.

Here are some of the more popular cultivated species of Cape Heaths —

Erica gracilis

It can be obtained with white flowers but the vast majority are shades of magenta. The shrub grows about 60cm high and is covered from top to bottom in 3mm urn-shaped flowers in early winter. It cannot withstand severe frosts but even when dead, it retains colour for the remaining winter months.

Erica pageana

A compact heath having rich buttercup yellow flowers, 8mm long, August to October (southern hemisphere). It reaches 45cm or so. Although it grows naturally in marshy conditions, it does not like cold damp conditions. The plant must be kept above -5°C.

Erica quadrangularis

Sometimes known as the Spring heather, this species comes in a wide range of colours from white to crimson. It is a very floriferous species and rightly very popular (including in north America). An erect shrub reaching 60cm. The flowers are about 3mm long. Like all Cape heaths, it is best kept in a light moist environment which is frost-free. Only very light pruning is required immediately after flowering.

Erica ventricosa

A very popular pot plant in north America and Europe. An erect shrub reaching 90cm. The pink flowers are hard, dry and wax-like and are about 15mm long. Although most pot plants offered for sale are hybrids of E. ventricosa, they should be treated in the same way as any Cape heath. Only very light pruning is required immediately after flowering.

South African gardeners wanting to remain true to the indigenous species should return to http://gardeningisezee.com/  soon, as I will be adding full profiles on a number of popular native Ericas to the Indigenous Plants section.