While the briefness of their glory has to be acknowledged, cherries really are the hardy spring-flowering trees for temperate climate gardens. I can think of no others, apart from their close Prunus relatives and some of the magnolias that even come close to rivalling flowering cherries for sheer weight of bloom and vibrance of colour.
The genus Prunus, to which the cherries, plums, almonds, apricots and peaches belong, includes around 430 species spread over much of the northern temperate regions and has a toehold in South America. Although including a few evergreen species, such as the well-known cherry laurel (Prunus laurocerasus), the genus is mainly deciduous and generally hardy to the frosts likely to occur in most New Zealand gardens.
The genus Prunus is widely recognised as being divided into 5 or 6 subgenera, though some botanists prefer to recognise these as distinct genera. The subgenus cerasus is the one to which the cherries belong. This group includes a wide variety of species, many of which are not highly ornamental. The species which are of most interest to gardeners are the Chinese and Japanese cherries, not only because they tend to be the most attractive, but also because they tend to be reasonably compact, often have attractive autumn foliage as well as spring flowers and because centuries of development in oriental gardens have produced countless beautiful cultivars.
The Japanese recognise two main groups of flowering cherries: the mountain cherries or yamazakura and the temple or garden cherries, the satozakura. The mountain cherries, which tend to have simple flowers, are largely derived from the original Mountain Cherry (Prunus serrulata var. spontanea), Prunus subhirtella and Prunus incisa. They are mainly cultivated for their early-blooming habit, which is just as well because their rather delicate display would be overwhelmed by the flamboyance of the garden cherries.
The garden cherries are the result of much hybridisation, mostly unrecorded, so we can’t be exactly sure of their origins. Prunus serrulata (in its lowland form) and Prunus subhirtella also feature largely in their background. The other major influences are Prunus sargentii, Prunus speciosa, Prunus apetala and possibly the widespread Bird Cherries (Prunus avium and Prunus padus). The result of these old hybrids and modern developments is the wealth of forms that burst into bloom in our gardens every spring. Regretfully, that complex parentage and those centuries of development and countless cultivars combined with Western misunderstandings of Japanese names and multiple introductions of the same plants under different names has led to considerable confusion with the names of flowering cherries.
Most of the popular garden plants are lumped together under three general headings:
1. Prunus subhirtella cultivars and hybrids;
2. Sato-zakura hybrids;
3. Hybrids no longer listed under parent species, being instead regarded as just to difficult to classify in that way.
But however you view them, flowering cherries have so much to offer that a little confusion over naming and identification shouldn’t stand in the way of your including them in your garden. And now that many of them are available as container-grown plants that can be bought in flower, it’s really just a matter of choosing the flowers you like. Nevertheless, it’s nice to know exactly which plant you’re dealing with, so that you can be sure of its performance and size. While most of the larger nurseries and garden centres take care to supply plants that are true to type, make sure on first flowering that your cherries match their label descriptions. Misidentification, or perhaps misrepresentation, is common.
Prunus subhirtella cultivars and hybrids
Although the flowers of Prunus subhirtella are usually small and fairly simple, they appear from early winter well into spring, depending on the cultivar. Not only that, the cultivars themselves are long-flowering, often being in bloom for three weeks to a month. There are many cultivars, but most are similar to, or forms of the two main types listed below.
‘Autumnalis’ ( ‘Jugatsu Sakura’)
This is the most reliable winter-flowering form. It often starts to bloom in late April to early May and can carry flowers right through until mid September. It seldom produces a massive burst of bloom, rather sporadic clusters of flowers. This is just as well because the flowers are damaged by heavy frosts. The flowers of ‘Autumnalis’ are white to pale pink opening from pink buds; those of ‘Autumnalis Rosea’ are the same but with a deep pink centre.
‘Pendula’ (‘Ito Sakura’)
Prunus autumnalis tends to have weeping branches and ‘Pendula’ is a cultivar that emphasises this feature. Its flowers are usually pale pink and open in late winter to early spring. ‘Falling Snow’ is a cultivar with pure white flowers, while those of ‘Rosea’ are deep pink.
Sato-zakura hybrids ‘Fugenzo’ ( ‘Shirofugen’ )
‘Fugenzo’ was one of the first, if not the first, Japanese cherry to be grown in European gardens. It ‘s origins can be traced back to at least the 15th century. Its flowers are white to very pale pink, opening from pink buds, and when fully open how two conspicuous green leaf-like pistils in the centre of the flower.
‘Taihaku’ , also known as the great white cherry, has white flowers up to 5cm across. It grows to at least 8m tall with a wider spread and its flowers open at the same time as its bronze foliage expands, making a pleasant contrast. Thought to have been lost to cultivation, this cultivar was identified in Sussex garden from an old Japanese print.
Although ‘Ukon’ mean yellowish, this cultivar has very distinctive pale green flowers and is one of the few unmistakable cherries. Its foliage develops purplish tones in autumn. The unusual flower colour contrasts well with the likes of ‘Sekiyama’.
‘Amanogawa’ grows to around 6m tall, but only around 1.5m wide, and has pale pink single flowers with a freesia-like scent. It blooms in mid-spring and in autumn the foliage develops striking yellow and red tones.
‘Shogetsu’ (‘Shugetsu’, ‘Shimidsu-zakura’)
‘Shogetsu’ flowers late and produces pendant clusters of white, double flowers that open from pink buds. The flower clusters are up to 15cm long, which makes a tree in full bloom an arresting sight, especially considering that ‘Shogetsu’ is not a large tree and that its weeping habit means it can be covered in bloom right down to the ground.
Certainly among the most popular cherries and most often sold under the name ‘Kanzan’, ‘Sekiyama’ has a relatively narrow, upright growth habit when young but eventually develops into a spreading 12m tall tree. Its flowers, which are pink and very fully double, are carried in pendulous clusters of five blooms. They open from reddish-pink buds. The foliage has a slight red tint.
‘Ariake’ (‘Dawn’, ‘Candida’)
This cultivar grows to about 6m tall and flowers in spring as the foliage develops. The young leaves are a deep bronze shade that contrasts well with white to very pale pink flowers.
‘Kiku-shidare’ (‘Shidare Sakura’)
‘Kiku-shidare’ is similar in flower to ‘Sekiyama’, but it has a weeping growth habit. It is a small tree and is often smothered in bloom from the topmost branches down to near ground level. The flowers can each have up to 50 petals.
‘Pink Perfection’ was introduced in 1935 by the famous English nursery Waterer Sons and Crisp. It is a probable ‘Sekiyama’ × ‘Shogetsu’ hybrid and has flowers that show characteristics of both parents; the clustered blooms of ‘Shogetsu’ and the pink of ‘Sekiyama’. The flowers are very fully double and the young foliage is coppery.
‘Kofugen’ has graceful semi-weeping branches and a fairly compact growth habit. Its flowers are not really single but semi-double, though the two whorls of petals are flat rather than ruffled, so the effect is not that easy to see.
‘Shirotae’ (‘Mt. Fuji’)
This beautiful tree has a spreading growth habit that in the best specimens shows distinctly tiered branches. Its flowers, which are white and semi-double on mature plants, start to open before the foliage expands. They are pleasantly scented.
Although possibly a Prunus × sieboldii cultivar, ‘Takasago’ is now more widely listed under the satozakura cherries. It bears clusters of semi-double pink flowers with bronze-red new foliage.
This tree, rather squat when young, but eventually 7m tall bears single white flowers in such profusion as to give the impression of double blooms. Opening from pink buds, the flowers are up to 5cm in diameter and among the later to bloom. ‘Ojochin’ means large lantern, which aptly describes the shape of the flowers.
Other hybrids, species and their cultivars
One of the most popular of all garden cherries, ‘Accolade’ is a Prunus sargentii × Prunus subhirtella hybrid that develops into a flat-topped small tree. In spring it is smothered in pendulous clusters of large, bright pink, semi-double flowers.
Yoshino cherry (Prunus × yedoensis)
Well-known as an avenue tree, this Prunus subhirtella × Prunus speciosa hybrid is smothered in white to very pale pink blooms in spring before or as the new leaves develop. When the flowers are spent they form drifts of fallen petals around the base of the tree. There are several cultivars, such as the pink-flowered ‘Akebono’, the pale pink ‘Awanui’ and a weeping form (‘Shidare Yoshino’ or ‘Pendula’).
Taiwan cherry (Prunus campanulata)
The Taiwan cherry is valued for its early-flowering habit and fiery autumn foliage. The flowers, which are usually a vivid deep pink, are heavy with nectar and very popular with birds. Taiwan cherry is rather frost tender, though once established it grows well in most coastal areas.
Introduced in 1947 by the British authority Collingwood Ingram, ‘Okame’ is a hybrid between the Taiwan cherry and the Fuji cherry (Prunus incisa). It is usually quite hardy, though this appears to be variable, and it flowers heavily in early spring. The blooms open in late winter to early spring before the foliage develops and are a bright soft pink. ‘Pink Cloud’ is a similar though more compact cherry raised by Felix Jury.
Himalayan hill cherry (Prunus cerasoides)
This species is rather frost tender, especially when young, but is a beautiful tree where it grows well. Not only does it produce pink flowers in winter, when little else is in bloom, it has attractive banded bark and the unusual habit of shedding its foliage in late summer then producing new leaves before winter. The variety rubea has deeper pink flowers in spring.
Cyclamen cherry (Prunus cyclamina)
Flowering on bare stems in early spring, the cyclamen cherry is a hardy small to medium-sized tree from central China. The flowers, which are rose pink, are followed by bronze new growth that retains its colour for some weeks before greening. The leaves fall late in autumn and often colour well.
Sargent’s cherry (Prunus sargentii)
This large and very hardy Japanese species is probably best known as one of the parents of the very popular hybrid ‘Accolade’. It can grow to as much as 18m tall and will withstand at least -25°C. Its 3 to 4cm wide, bright pink flowers are complemented by red-brown bark.
Kurile cherry (Prunus nipponica var. kurilensis)
Usually little more than a large shrub, this Japanese cherry can reach 6m tall under ideal conditions. The flowers, which are soft pink and open from early spring, are backed by red sepals that hang on for a while after the flowers have fallen, thus prolonging the spring colour.
Prunus × sieboldii
This hybrid has given rise to several popular cultivars. The original cross is a slow-growing small tree with semi-double 3 to 4.5cm wide flowers in spring. The new stems are often very glossy.
Flowering cherries are largely undemanding plants that thrive in almost any well-drained soil. For the best display of flowers they need to see at least half-day sun and if sheltered from the wind, the blooms and the autumn foliage will last far longer than if exposed to the full blast of the elements.
Cherries are often seen growing as lawn specimens, but they can be planted in shrubberies, borders or small groves. By choosing a selection that flowers in succession, it’s possible to have bloom from mid-winter to early summer. Cherries are natural companions for azaleas and rhododendrons, and can be used to beautiful effect as shade trees for the smaller varieties of these or to shelter a collection of woodland perennials such as primroses and hostas. Japanese maples also blend well with cherries and they can combine to make a brilliant display of autumn foliage.
Flowering cherries seldom need major pruning once established. Young trees can be lightly trimmed to develop a pleasing shape and mature plant may be kept compact by tipping the branches, otherwise just remove any vigorous water shoots and suckers that sprout from the rootstock. Make sure that any pruning is done in summer to prevent infecting the trees with silver leaf fungus (Chondrostereum purpureum). Although this disease is present throughout the year, cherries are most resistant to it in summer.
Pests and diseases
Apart from the already mentioned silver leaf, there isn’t really very much that goes wrong with flowering cherries that can’t be tolerated. Sawfly larvae (peach or pear slug) sometimes cause damage to the foliage, and older plants sometimes suffer from dieback in their older branches, but these are seldom serious problems. The dieback is sometimes the result of Armillaria, so it may be advisable to insert some of the now readily available Trichoderma dowels into the trunks of any older cherries to prevent the problem developing.
Virtually all of the fancier flowering cherries sold for garden use are budded or grafted, usually onto Prunus avium stocks. Although few home gardeners attempt them, these processes are not difficult. Budding especially, is straightforward and is carried out in exactly the same way as budding roses.
Species, including the standard Prunus avium stock, can be raised from seed or from softwood cuttings taken in spring or early summer. The seed should be removed from the fruit by soaking for few days until all the flesh has fallen away. It is usually best to simulate winter conditions by chilling the seed for a few weeks before sowing.
When buying flowering cherries you may be faced with a choice of graft height. Which you choose largely depends on the cultivar and the type of growth best suited to your garden. With weeping cherries choose the highest graft possible (usually 8ft [2.4m]), to allow the maximum length of flowering branch. Upright cultivars like ‘Sekiyama’ are best grafted near ground level so that their erect habit has a chance to develop properly, while graft height in not that important with bushier trees.
The important thing to remember, particularly with high grafted plants, is that the main stem will not gain much height from the grafting point. The stems of a weeping cultivar may grow up before arching down, thus adding some height, but if you choose too low a graft that won’ t make much difference. Low-grafted weeping cherries are, however, ideal for large tubs where they can be kept trimmed to shrub-like proportions.