Cotoneasters are easy-to-grow, red-berried shrubs that include species suitable for screening and hedges, as well as for training on walls. The two varieties most suitable for screening are both semi-evergreen: C. x watereri, which can go as high as 4.6m (15 ft), and C. x ‘Cornubia’, which will grow to 5.5m (18 ft) or more, and spread almost as wide. When used as a screen, C. x watereri should be planted 1.5 m (5 ft) apart, and C. x ‘Corriubia’ 2.1 m (7 ft) apart, at least. These planting distances will give a very thick screen, and can be exceeded and still give satisfactory screening eventually. Another semi-evergreen is C. simonsii, seldom growing above 2.1 m (7 ft) but, because of its upright habit of growth, suitable for a screen or hedge.
Plantings for the latter use should be 30 cm (12 inches) apart. C. franchetii, up to 2.4m (8 ft) high and C. lacteus 3.6m (12 ft) are both evergreens, and are excellent for hedging when, again, they should be planted about 30 cm (12 inches) apart. C. horizontal is is a deciduous species whose shoots and laterals form a regular herringbone pattern which looks very effective when trained on a wall or wooden fence and as it is deciduous, you get the bonus of the autumnal tints before-fall. It will reach a height of 1.8m (6 ft) to 2.4m (8 ft) when trained in this way.
All the cotoneasters are capable of producing showy crops of berries, scarlet or crimson in most varieties, but many are also first-rate foliage shrubs with an interesting diversity of habit andshape. Cotoneaster dammeri is completely prostrate, making a carpet of evergreen ideal as covering for a bank or under other shrubs. C. horizontalis has a curious fishbone habit of branching and will make a wide low bush in the open or spread itself flat like a climber against a wall or fence. Its small turn orange and scarlet before they fall in autumn.
C. microphyllus has small, dark green, evergreen leaves and its branches will mould themselves to any solid object or mound themselves into low, wide bushes. C. conspicuus decorus, making a bigger, dome-shaped bush, is also evergreen and notably free fruiting. C. franchetii sterni anus is semi-evergreen, of open shuttlecock habit and C. salicifolius is fully evergreen and has a number of forms, some spreading, some erect. Finally there are large, almost tree-like kinds, such as C. frigidus, which is deciduous and has a yellow-fruited variety named fructu-luteo, and scarlet-fruited hybrids such as cornubia and watereri which can reach 15 ft. or more.
All are very adaptable as to soil andand, though is not essential, or branches can be shortened or removed in spring if bushes occupy too much room, and when used as hedges they can in addition be trimmed lightly in summer.
General care: Cotoneasters are not fussy about site or soil, and in fact seem to prefer poor soil. Plant any time in the winter, and if growing for hedging, shorten the shoots to encourage a bushy growth habit. Routine pruning is not needed, but hedges should be trimmed.
Propagation: Cotoneaster can be grown easily fromharvested in the autumn, but are unlikely to grow true to type. It is better to use heeled , taken in late summer and struck in a 50-50 peat and sand mixture, or to layer some shoots, which can then be separated from the parent a year later.
Pests and diseases: Birds often eat the berries.can be sprayed with malathion. Fireblight, which is on the increase, can affect cotoneaster. Its symptom is dark brown, shrivelled leaves. It is caused by a bacterium, and there is no chemical cure. Infected branches should be cut back well below the infected area and burned, and the secateurs should be disinfected afterwards. (Fireblight is a notifiable disease.)