Groundcover Cotoneasters...Multipurpose Shrubs
(Editor's Note: This article was originally published on May 8, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Certain genera of shrubby plants are staples in the garden landscape. Potentilla, Spirea and Weigela are such examples. Not all garden staples are grown for their flowers. Some like hollies, are more important for their decorative fruit production. Others, like burning bush, are grown for their excellent fall colour. A few choice garden shrubs have the potential to offer all three...blooms, fruit and excellent fall colour. The main genus to comes to mind are the Cotoneaster.
The genus Cotoneaster has some 70 or so species and many hybrids. In the wild, they are mostly restricted to Eurasia, with a few that stretch into north Africa. They are members of the Rose family, along with many of our fruit-producing trees and shrubs such as cherries, plums, apples and mountain-ash, just to name a few. Being such a large group, cotoneasters show great diversity in size and form. Some are quite small and dwarf, making them suitable for alpine gardens and troughs. Other form large shrubs, almost tree-like. The flowers are generally white or pink-tinted and mat be solitary or in clusters. The fruit, which are often persistent through the winter, are mostly bright orange-red but yellow and black-fruited species exist. The berries are eagerly sought by fruit-eating birds such as robins and waxwings. There are both deciduous, which have brilliant orange-red-burgundy fall colour and evergreen species and hardiness ranges from those that can tolerate zone 4 to those which are almost sub-tropical with only slight frost-resistance. Bottom line, for those who garden in zones 4-9, there are at least a few cotoneaster suitable for your garden. The emphasis of this article will be the hardier, lower-growing species, which are probably the most popular Cotoneaster with most gardeners. The more upright types may be the focus of a later article.
Cotoneaster have no particular cultural demands. Any soil that is not too boggy will suit them, even relatively poor soils. In the wild, they generally grow in limestone areas, so for gardeners who have acidic soil, a yearly dusting of lime may be beneficial. They are very tolerant to pollution, making them ideal urban plants. Full sun is best, but many will tolerate part shade. Weekly watering is fine. Like most members of the rose family, they have their share of insect and disease problems. The main disease is fireblight, although the smaller, creeping species are less susceptible than the taller, upright species. Insects that attack apples, can potentially attack cotoneaster. In my own garden, pearslugs and the larvae of some nondescript small moth, can be a problem but insecticidal soap seems to work fine to keep them under control. Spider mites may also be a problem during hot, dry weather.
Among the hardier, low-growing species are selections from C. adpressus, C. apiculatus, C. dammeri, C. horizontalis and C. microphyllus. Many selections from these five species are grown as groundcovers, foundation plants or subjects for large rock gardens. Many look particularly attractive spilling over rock walls. They are all native to western China.
Cotoneaster adpressus or creeping cotoneaster, has trailing stems to several meters, however, they rarely exceed 30 cm in height. Their leaves are dull, dark green, somewhat rounded with wavy margins. The fall colour is not as bright as some species, mostly burgundy-purple shades. The flowers are pinkish-red and produced singularly or in pairs, followed by dark red berries. This species is relatively drought-resistant once established. Plant them 1 m apart if using them as a groundcover. The cultivar ‘Little Gem' (aka ‘Tom Thumb') is quite dwarf only 15 cm tall with a spread of 30-45 cm, making it ideal for smaller rock gardens and alpine troughs. However, this dwarf cultivar rarely flowers or fruits. Zone 4-7.
Cotoneaster adpressus and the more compact cultivar called 'Little Gem' or 'Tom Thumb'
Cotoneaster apiculatus is commonly called the cranberry cotoneaster. In the wild, they may reach 2 m but those which have been selected as garden ornamentals, are low, sprawling shrubs. They look nearly identical to creeping cotoneaster but their leaves are glossy, not dull, and the plants may reach 45 cm in height. Their berries are brighter red and more numerous than those of creeping cotoneaster and the fall colour is also brighter, however, this species is not as drought-tolerant as the previous. Overall, cranberry cotoneaster is more popular than the creeping. Zone 4-7.
Cotoneaster apiculatus details
Cotoneaster dammeri or bearberry cotoneaster, is a moderately fast growing, evergreen groundcover with long trailing stems over 3 m in length yet the overall height of the plants is only 45-60 cm. It is a premier groundcover with glossy leaves all season. The bright white, fragrant flowers, although produced singularly, are often numerous and reasonably showy. The bright red fruit contrast beautifully with the dark green leaves. They are not as hardy as the previous two species being rated for zone 5-9 and in severe winters, they may be semi-deciduous in the colder zones. ‘Coral Beauty' is the most popular cultivar of bearberry cotoneaster on the market. ‘Lowfast' is perhaps the quickest growing selection and rarely tops 30 cm in height. The cultivar ‘Moner' aka ‘Canadian Creeper' is even lower, growing to 15 cm in height. This latter one is quite similar to 'Streibs Findling' which is also completely prostrate.
Cotoneaster dammeri 'Coral Beauty' details
Cotoneaster horizontalis or rockspray cotoneaster, is perhaps the handsomest and most architectural of the cotoneasters. This species produces overlapping, flat, fan-like branching pattern that is distinctly reminiscent of herringbones. In or out of leaf, this pattern is unmistakable. The small, glossy green leaves turn brilliant scarlet in autumn. The flowers are pinkish-red and not particularly noticeable but the bright red fruit is produced in vast quantities, making this species one of the most useful for berry production. Plant will reach to 1 m in height with 2 m spread. They are very wind tolerant but appreciate regular watering. The one drawback is that this species is more susceptible to fireblight than C. adpressus or C. apiculatus. This species is hardy from zones 5-8 and even into zone 4 if there is reasonable snowcover. The cultivar ‘Variegatus' has grey-green leaves edged in white.
Cotoneaster horizontalis details; the last image is the variety 'Variegatus'.
Cotoneaster microphyllus or littleleaf cotoneaster, is the smallest, slowest growing of these low cotoneasters. It is also the least common but useful for those who have limited space or are looking for good shrubs for containers, bonsai or smaller rock gardens. Plants form evergreen mounds about 60 cm in height and 1.2 m spread. The leaves are under 1 cm in length, fairly narrow and glossy deep green. The white flowers develop into a good display of red fruit. The variety ‘Thymifolius' has the smallest leaves of any cotoneaster, almost needle-like. The variety ‘Cochleatus' is sometime listed as a species, but is overall very similar to C. microphyllus except that the leaves and plant are a little larger. They are hardy from zones 5-9.
Details of Cotoneaster microphyllus
Whether you are looking for a shrub to grow as a groundcover, attractive fruit-producer, wildlife attractant or producer of good fall colour, you can find the right selection among the low cotoneasters.
I would like to thank Equilibrium for the use of C. horizontalis 'Variegatus' and ron_rothman for the use of C. adpressus 'Tom Thumb'.