Heather (Calluna vulgaris)

Scotch heather (Calluna vulgaris) is an evergreen flowering shrub that produces hundreds of rose-pink to purplish-pink, bell-shaped flowers that bloom in late summer. Relatively low maintenance, it is perfect in rock gardens or used as a border or ground cover.

I. Appearance and Characteristics

Calluna vulgaris, common heather, ling, or simply heather, is the sole species in the genus Calluna in the flowering plant family Ericaceae. It is found widely in Europe and Asia Minor on acidic soils in open sunny situations and in moderate shade.

Calluna vulgaris is native to Europe, Iceland, the Faroe Islands, and the Azores. It has been introduced into many other places worldwide with suitable climates, including North America, Australia, New Zealand and the Falkland Islands. It is extremely cold-hardy, surviving severe exposure and freezing conditions well below −20 °C (−4 °F).

Calluna has small-scale leaves (less than 2–3 mm long) borne in opposite and decussate pairs, whereas those of Erica are generally larger and in whorls of 3–4, sometimes 5. It flowers from July to September. In wild plants these are normally mauve, but white-flowered plants also occur occasionally. They are terminal in racemes with sepal-like bracts at the base with a superior ovary, the fruit a capsule. Unlike Erica, Calluna sometimes sports double flowers. Calluna is sometimes referred to as Summer (or Autumn) heather to distinguish it from winter or spring flowering species of Erica.

Phenolic compounds in the shoots of Calluna vulgaris include chlorogenic acid and a novel phenolic glycoside, most of which are found in greater numbers during the summer.

The nectar of Calluna vulgaris contains a megastigmane, callunene, that is inhibitory at naturally occurring concentrations to a common trypanosome parasite of bumble bees, Crithidia bombi. Koch et al. elucidate the mechanism of activity that results in the loss of the parasite’s flagellum, leading to reduced infectivity, because the flagellum is crucial to anchoring in the insect gut.

It is the dominant plant in most heathland and moorland in Europe, and in some bog vegetation and acidic pine and oak woodland. It is tolerant of grazing and regenerates following occasional burning, and is often managed in nature reserves and grouse moors by sheep or cattle grazing, and also by light burning.

II. How to Grow and Care

Sunlight

Heather blooms best in full sun in zones 4 and 5. In zone 6, it will appreciate afternoon shade.

Temperature and Humidity

Heather likes a climate that is moist and cool. A heather’s evergreen foliage changes and intensifies in hue during cooler temperatures. Calluna is typically hardy in zones 5 to 7 but may thrive as far north as zone 3 with adequate winter protection or snow cover. It cannot tolerate high temperatures and humidity in the southern U.S.

Watering

Scotch heather should be watered twice per week when young and the soil should be kept lightly moist. The soil should not be allowed to dry out completely between waterings. Overwatering can lead to root rot. Established Scotch heather barely needs any watering.

Soil

Heather requires well-drained soil and does well in sandy soils or rocky terrain. It thrives in peaty, more acidic bogs and moorlands. It does not need fertile soil, it can thrive in poor soils and can tolerate salt spray.

Fertilizing

As long heather has some organic matter or peat moss in its soil, it does not need additional nutrients. Heather prefers acidic soil; you can give an acidifying nitrogen fertilizer made especially for acid-loving plants such as rhododendrons once a year in early spring. If you are going to give fertilizer, provide no more than one pound per 100 square feet and no later than August 1. Added any later, it will spur growth during the winter when the plant should be dormant. Excessive fertilization tends to cause leggy, spindly branches.

Pruning

Pruning heather is essential to maintain healthy growth and abundant flowering. Do this in spring, around March or April, when the weather is cloudy. Cut back last year’s new shoots by about half. The plants are not particularly sensitive to pruning and, for large areas, it can also be done with hedge shears or a brush cutter.

Propagation

Heather grown from seed will not reproduce true to the parent plant. The best way to propagate heather is by taking cuttings in the summer, rooting them indoors over the fall and winter, and planting them outdoors in the early spring.

You’ll need a six-inch growing pot, vermiculite or a soilless mix, an inch of compost, sterilized pruners, rooting hormone, and a clear plastic bag.

• Choose a six-inch green, non-woody stem. Cut a branch with two leaves and cut it just below a node.
• Dip the cut end in the rooting hormone.
• Fill the pot at the bottom with an inch of compost or organic matter. Fill the rest of the pot with vermiculite or soilless mix. Make a hole in the soilless mix with your finger, or optionally, a pencil. Place the cutting in the hole and gently pat down the soil around the stem.
• Water the plant and put the pot in indirect sunlight.
• Create a tent above the pot with a plastic bag to give the plant humidity, encouraging rooting. Uncover the plant for about an hour a day to get fresh air circulation. Once you notice new growth, remove the plastic bag entirely. It should take about one month for the cutting to root. Replant outdoors in the spring after the frost threat is gone.

How to Grow from Seed

In its natural habitat, heather seeds germinate best after a wildfire. Mimic these conditions to spur germination in the spring or fall. For best results, you’ll need an oven or smoker, a pot or seed tray, vermiculite or soilless mix, and a water spray bottle. Here’s how to grow heather from seed.:

• Spread seed over a fire-resistant tray and put the tray in an oven at 250 degrees Fahrenheit for 30 seconds. Alternatively, smoke may help with sprouting heather seeds, so place them in a smoker on low heat, for about two hours.
• Fill a seed tray or pot with a soilless mix.
• Sow seed on top of the mix. If using a pot, do not put more than three seeds in a pot, spacing them at least an inch or two apart.
• Sprinkle a handful of soilless mix over the seed, lightly covering them.
• Using a spray bottle, dampen the soil.
• Put the tray in indirect sunlight.

Potting and Repotting

Plant heather in a large, wide pot, one size bigger than the previous one with good drainage holes in the bottom. Although it should not be too shallow, Heather does not need a deep planter. This plant can stay at the same depth as its nursery pot or only as deep as the plant’s root ball. It does well in clay pots.

Overwintering

Heather is a hardy plant. However, in zone 4 or northward, protect potted heathers by insulating the plant. Cover the pot with polystyrene foam (also from the bottom) and mulch the plant heavily with a layer of straw. Smaller pots can be taken indoors and grown under grow light or near a window with indirect sunlight.

Pests and Diseases

Common Plant Diseases

Heather is susceptible to powdery mildew and root rot, which you can avoid. Powdery mildew does not kill heather, but this fungal disease can mar its appearance. It takes the form of a dusty-looking covering on a plant’s foliage.2 Its leaves are evergreen and develop attractive tones in fall and winter (bronze or purple tones). As it’s a foliage plant, powdery mildew can spoil one of the plant’s best features. To prevent powdery mildew, avoid overhead watering. Prune faithfully every spring to keep plants compact, thereby improving airflow. If powdery mildew affects your heather, use an off-the-shelf fungicide or a baking soda solution.

Waterlogged soil is usually the culprit behind root rot, especially if the Phytophthora fungus is present. Phytophthora is rarely an issue in soil that drains well, reinforcing the need to provide your heather with sharply draining soil.

Common Problems With Heather

Heather is a hardy, easy-growing plant that is not susceptible to many issues beyond fungal growth as a result of overwatering.

Browning Foliage

If your heather plant’s foliage starts browning, touch the leaves to see if they’re dry and brittle—a sign that the plant is dying. Break off a single stem of the plant. If it’s pliable and green or white inside, it’s still alive; if it snaps in half easily, it is likely dying or dead.

Usually, sudden death in the middle of the growing season is a sign of root rot. You’ll need to pull up the plant, dispose of it, and not plant heather in that same spot for a few years. If the plant still has signs of life, it might have drainage issues. Pull it up and inspect the root system. If the roots have turned dark brown or black, cut away the rot using sterilized scissors. Apply an antifungal and replant it in well-draining soil new soil in a new spot; this action may save the plant.

Leggy Stems

Heathers thrive in poor soil. A non-fertile soil encourages the roots to branch out in search of nutrients, which gives them deep, sturdy root systems. If the soil gets fertilizer, then the soil has too much nitrogen, resulting in weak root systems and excessive vegetative growth or longer stems. Also, if the plant is not getting enough light, stems may grow out in search of more sun. To prevent or reverse legginess, stop giving fertilizer and place the plant in a sunnier spot. You can also trim the leggy stems in spring or early fall to encourage healthy growth.

Distorted Leaves or Leaf Drop

If you notice your plant’s leaves turning yellow, stippling, or mottling, you might have a mite infestation. Carefully inspect the plant, overturning the leaves. Mites are hard to see. But, you might notice red or yellow dots or some webbing. A steady stream of water on the undersides of leaves for three days may be enough to eliminate the problem. Otherwise, use insecticidal soap or horticultural oil all over the plant.

Check for small, hard oval-shaped bumps on the stems. These bumps may be scale insects that can cause leaf drop and distorted leaves. Scale insects can be picked off, and horticultural oil and insecticidal soap can also help control scale infestations.

III. Uses and Benefits

• Garden Use

Scotch heather is a very attractive and popular choice of heather for the garden, being fast-growing and having great color. It looks excellent planted en masse, especially on hills and slopes. Smaller shrubs look good in a rock garden too. It is often combined with dwarf conifers and various deciduous shrubs for variation in color and texture.

• Other uses

Heather is an important food source for various sheep and deer which can graze the tips of the plants when snow covers low-growing vegetation. Willow grouse and red grouse feed on the young shoots and seeds of this plant. Both adult and larva of the heather beetle (Lochmaea suturalis) feed on it, and can cause extensive mortality in some instances. The larvae of a number of Lepidoptera species also feed on the plant, notably the small emperor moth Saturnia pavonia.

Formerly heather was used to dye wool yellow and to tan leather. With malt, heather is an ingredient in gruit, a mixture of flavorings used in the brewing of heather-beer during the Middle Ages before the use of hops. Thomas Pennant wrote in A Tour in Scotland (1769) that on the Scottish island of Islay “ale is frequently made of the young tops of heath, mixing two thirds of that plant with one of malt, sometimes adding hops”.

From time immemorial heather has been used for making besoms, a practice recorded in “Buy Broom Buzzems” a song probably written by William Purvis (Blind Willie) (1752–1832) from Newcastle-upon-Tyne, England.

Heather honey is a highly valued product in moorland and heathland areas, with many beehives being moved there in late summer. Not always as valued as it is today, it was dismissed as mel improbum, “unwholesome honey” by Dioscurides. Heather honey has a characteristic strong taste, and an unusual texture, for it is thixotropic, being a jelly until stirred, when it becomes a syrup like other honey, but then sets again to a jelly. This makes the extraction of the honey from the comb difficult, and it is therefore often sold as comb honey.

White heather is regarded in Scotland as being lucky, a tradition brought from Balmoral to England by Queen Victoria and sprigs of it are often sold as a charm and worked into bridal bouquets.

Heather stalks are used by a small industry in Scotland as a raw material for sentimental jewelry. The stalks are stripped of bark, dyed in bright colors and then compressed with resin.

Calluna vulgaris herb has been used in the traditional Austrian medicine internally as tea for treatment of disorders of the kidneys and urinary tract.