Cotoneaster, Dwarf whitebeam
Evergreen foliage, lush flowers, bright red fruits - cotoneasters are true all-rounders. This is how you plant and care for the versatile garden shrubs.
Around 90 species of dwarf whitebeam or cotoneaster belong to the family of pome fruit plants (Pyrinae) and, like Firethorn (Pyracantha) and Shadbush (Amelanchier) are members of the species-rich rose family (Rosaceae). They come from the temperate latitudes of Asia (especially China and the Himalayas), Africa and Europe, with the low-growing species seen in mountain regions at heights of up to 13,123.36 feet.
The Latin name Cotoneaster comes from Roman times and means something like "useless quince". However, this name does not do justice to the dwarf whitebeams. By the way: The botanical nomenclature identifies both the female and the male form of cotoneaster when naming it, with the male being the correct Latin name. The term cotoneaster is slightly misleading, because it does not describe the size of the plants, but the size of their fruits.
Appearance and Growth
Cotoneasters come in many low-lying and creeping species and forms, but depending on the species they can also grow into trees over 32.80 feet high. However, cotoneasters always tend to grow in width, which you should consider when planning your garden or flowerbed. The dwarf whitebeams are characterized by their dense foliage with small, dark green, glossy leaves that remain on the shrub in many Cotoneaster species even in winter. Its flowers appear in white, pink or red in May and June and are usually grouped in small clusters, bunches or panicles. From them, red or yellow fruits, which visually resemble very small apples, emerge in fall.
These fruits are a popular bird food late into winter. The fruit hangings of the wrinkled cotoneaster (Cotoneaster bullatus) has even earned it the nickname "blackbird tree". The flowers attract many bees and butterflies. That is why dwarf whitebeams are one of the most important fodder crops for the local fauna. Cotoneaster contains the glycoside amygdalin, which is similar to hydrogen cyanide, which is why all parts of the plant, including the fruits, are slightly toxic to humans. Serious health consequences only occur when larger amounts are consumed.
Location and Soil
All cotoneasters prefer a sunny to partially shaded location and nutrient-rich, well-drained soil that can be lime-rich. The sunnier the place, more abundant the flowers. Overall, however, cotoneasters are extremely adaptable and can cope with adverse location conditions - only waterlogging is what they can’t tolerate. The shrubs, on the other hand, cope fairly well with heat and temporary drought. For this reason and because they spread quite quickly, cotoneasters in some countries they are listed as invasive plants and import is completely prohibited in some countries - for example in Switzerland.
Planting the cotoneaster
The cotoneaster is planted in winter between October and May. Before planting, the soil should be loosened and cleared of weeds. Heavy soils can be improved with the addition of gravel or sand. Especially if the cotoneaster is to be used as a groundcover, it is important to thoroughly remove all weeds first. The planting distance depends on the desired density of the subsequent vegetation and the variety, but should not be less than 19.68 inches so that the plants have enough space to grow. Most cotoneasters are sold as container plants and can therefore be planted all year round.
Just before planting, you should immerse the root ball in a bucket of water until air bubbles stop coming up. After planting, the bushes must be watered well and the root ball should never dry out in the first few weeks. Pruning immediately after planting ensures that the shrubs branch out well and cover the ground thoroughly. Some dwarf whitebeam varieties are also well suited for planting in containers. In some cases, slow-growing varieties are also sold as grafted tall plants, which are also very attractive in the container on the terrace.
Dwarf whitebeams are one of those shrubs that grow easily with a minimum of care and are beautifully decorated with flowers and berries. A base fertilization with compost and horn shavings at the beginning of the growing season is advantageous in the first few years after planting so that a newly laid plant covers the ground quickly. If the summers are hot and dry, it should also be watered extra from time to time. A protective mulch cover keeps the moisture in the soil. For healthy growth in cramped conditions, container plants need regular fertilizers throughout the year. For some species, you should also ensure good winter protection in the container. In case of a mild winter, don't forget to water it.
Dwarf whitebeams are very easy to cut. Regular, generous pruning ensures that the plants are rejuvenated and that they branch well, but this is not absolutely necessary. In particular, you can prune the ground-covering species vigorously if necessary. They can also tolerate cutting back into older wood. Shrubby species are only thinned out. If they take up too much space, the younger parts of the branch can be shortened to a side branch. The time of cutting depends on the species of Cotoneaster: Evergreens are best cut in the spring before they sprout new shoots. Deciduous varieties are cut in late winter. If you want to enjoy the bloom, it is also possible to cut back around St. John's Day (June 23). Shape cuts for cotoneaster borders can also be done at this time. You can remove interfering or dead shoots near the ground at any time. Unlike the related Firethorn, Dwarf Whitebeams have no spines or thorns. That makes pruning a lot more easy.
Where to plant
For a long time, particularly creeping cotoneaster species and their garden varieties were mainly used for easy-care locations and embankment greening in public green spaces and on traffic islands, as well as for grave planting. This has given the decorative shrubs a dubious reputation: For example, some landscaping companies were called "ABC bombers" - "ABC" stood for asphalt, concrete and cotoneaster.
But now you can see cotoneaster species more and more in home gardens - not only as a groundcover, but also as edging hedges, companion for roses and even solitary shrubs. The slow-growing, low-lying species can also be planted in the rock garden. Taller species can be cut into hedges or topiary trees or integrated as groups of shrubs in forest borders.
Important Species and Varieties
Among the elegant, tall representatives, the showy cotoneaster (Cotoneaster multiflorus) is one of the most decorative shrubs. As individual plants, the 6.56 to 9.84 feet high deciduous shrub - like most cotoneasters - is much wider than it is tall. The arched branches with their white, fragrant flowers hang over like a drape. There are many varieties of Bearberry cotoneaster (Cotoneaster dammeri) that are ideally suited for greening areas. The groundcover “Queen of Carpets” (Cotoneaster dammeri) is only about 5.90 inches high and also grows mainly in width. Six plants per 10.76 square feet are enough to cover the ground well. In May and June the groundcover blooms in light pink, later its red berry decoration provides color.
The bearberry cotoneaster “Juliette” (Cotoneaster dammeri) catches the eye with its two-tone leaves. Often the area cover, which is up to 51.18 inches higher, is also sold as a high stem. The berries often remain until spring. The Rockspray cotoneaster (Cotoneaster horizontalis) stretches over stone edges, plants green walls and, with its orange-red fall color, sets accents between perennials and other small shrubs. It grows up to 6.56 feet high on garden walls and overwhelms them on the other side. The almost horizontally protruding, regularly arranged side branches, which give the branches the appearance of a herringbone, are very striking. The bright green leafy cultivar Cotoneaster ‘Rothschildianus’ with its pale yellow fruits and the very spreading, approximately 19.68 feet high growing species Cotoneaster x watereri ‘John Water’, which bears blood-red fruits, were awarded prizes by the Royal Horticultural Society. The variety ‘Cornubia’ (Cotoneaster watereri) is one of the most beautiful evergreen shrubs with its dense, light red trimmings. It can be up to 13.12 feet high.
Propagating cotoneaster is a breeze in most cases: It is best to cut 3.93 inches long stem from existing plants for propagation cuttings. Remove the leaves at the lower end, place in potting soil and cover with foil. If you keep the substrate evenly moist, the rooting is usually quite reliable. While sowing it should be noted that cotoneasters are cold germinators. In early winter, sow the seeds in a seed tray and let them swell in a warm place for a few days. The pot is then placed outside in a sheltered place over the winter for stratification. From March the seeds germinate quite reliably. However, sowing only makes sense for wild species - the numerous garden forms cannot be propagated in this way.
Some higher varieties such as “Cornubia” are often propagated in January by grafting, mostly by splice grafting or the so-called goat's foot graft. However, both methods are better handled by professionals.
Diseases and Pests
The cotoneaster is unfortunately more often attacked by what is known as fire blight. The bacterium called Erwinia amylovora penetrates the plant via young shoots and flowers in spring and summer and causes leaves, shoots and young fruits to wither and die off rapidly. The affected parts of the plant curve downwards, turn black and look like they have been burned. Fire blight can spread like an epidemic and quickly spread to other stone fruit. Affected plants must therefore be cleared immediately and the infestation reported. It is therefore advisable to keep a sufficient distance from fruit trees when planting in the garden. In addition, aphids and mealybugs like to feed on Cotoneaster - they are also the main vectors of fire blight.