Pruning: A-Z of Trees, Shrubs and Climbers
This page comprises a comprehensive A-Z list of the 100 most popular trees, shrubs and climbers. Therequirements of each are explained, and in the majority of cases we discuss whether the plants are tender or hardy in the North European climate.
The letters following each generic name are abbreviations, as follows:
Most species are tender and need a sheltered position or wall. In the spring, remove winter damage, thin crowded shoots and remove some old wood.
All species are tender and usually grown as wall shrubs. In late spring cut out winter damage and thin out crowded shoots. Abutilon vitifolium should be treated as a free-standing shrub and succeeds best where there is some summer humidity; the only pruning needed is dead-heading.
Acer (maple) DS/T
A large family of varying habits, size and attractions all of which have to be considered when pruning.
Trees are trained to a central leader. If the leader is lost a new one must be trained in or the opposite buds will result in two leaders; in some species it is difficult to retain a leader. Carry out pruning when fully dormant as some species bleed if cut when the sap is rising. Bushes may be allowed to have several leaders though often a central one is trained in but with all side shoots retained.
Coloured leaf forms of A. negundo should never be pruned hard, otherwise the resulting shoots revert to green. Training in the early days should consist of little more than pinching. Those trees grown for their bark should have their trunks exposed as soon as possible; an annual trimming of the previous year’s growth on the snake bark maples will result in long, colourful young stems.
Slightly tender, vigorous twiners that need plenty of space. Once a well-spaced framework has been achieved by training in several long stems opposite and parallel, young stems are cut back in mid-spring to within two or three buds of this framework; repeat the process in mid-summer so as to build up a spur system.
For pruning purposes, there are two types: one suckers and remains a shrub, the other becomes tree-like. The first is pruned in mid-winter when the oldest stems are removed; in the second form, a central leader is trained, all side shoots being reduced but retained as long as possible.
All are strong growers and need plenty of space. They are well suited for growing through a tree where no pruning is required. If space is restricted train in a number of rods (mature shoots) and in mid-winter cut back all young shoots to within two or three buds of the rods. Bleeding will follow if pruning is delayed until the sap begins to rise.
Trim to shape in mid-spring, occasionally cutting out some of the oldest wood. This shrub will respond to hard pruning if it becomes too large.
Azalea see Rhododendron
Some evergreen kinds are tender and need shelter. However, all evergreen types should be pruned after flowering; if berries are desired, delay pruning until the following spring, when those shoots having borne fruit should be removed.
Most deciduous barberries form dense thickets, and these should be thinned in mid-summer, removing completely at ground-level. If old bushes become unmanageable they can be cut down to the ground after flowering.
Many species are tender and need a south or west wall for protection; these are trained fan-wise, ensuring that the lowest part of the wall is kept clothed.
Buddleias which flower on current season’s growth, for example B. davidii (butterfly bush), are cut hard back to a framework in the winter; tender species are similarly treated in mid-spring. Buddleias which flower on the previous year’s growth, for example B. globosa (orange ball tree), are pruned when the blooms have faded; the shoots which have carried theare removed.
Buddleia albernifolia is best treated as a standard. Select the strongest shoots, remove the others, and tie to a stake; continue feathering until there is a clear stem of at least 1.2 m (4 ft), after which natural development can be allowed.
Buxus (box) ES/T
If of tree form, select a single leader, removing competition; side shoots are reduced but retained as long as possible except if too crowded. The bush kinds, of which there are many different forms, should be trimmed to shape in mid-spring when some corrective pruning may be necessary, especially if heavy snow has caused any damage.
Calluna (ling) ES
Trim over the clumps in early spring, removing old flowers and most of last year’s growth. Plants grown just for foliage are often best trimmed as the flower spikes form for the colours of flower and foliage often clash.
Some species are tender and need wall protection. C. japonica and its many forms are hardy though often flower-bud tender. Dead-heading is desirable on those kinds which do not shed their spent flowers; at the same time trim to shape or restrict growth.
Camellia japonica sports freely and several colours can appear amongst flowers on one bush. Branches bearing different-coloured flowers should be traced to their source and removed. Camellia sasanqua and C. cuspidata are autumn-flowering species and if pruning is necessary carry this out in mid-spring.
Tender species and some of the forms of C’. japonica may be grown as wall shrubs. Fan train a well-spaced framework and allow side branches to develop just sufficiently to fill the intervening spaces; remove surplus shoots as well as any coming away from the wall.
These slightly tender climbers need full sun and a south wall. They are strong growers, attaching themselves to supports by climbing roots. Once a well-spaced framework has been trained with the lower part of the wall well-clothed, all side shoots should be cut back in early spring to within two or three buds.
Caryopteris (blue spiraea) DS
Unless the wood is thoroughly ripened, die—back is common. In mid-spring cut back all young shoots to a framework, which is best trained on a short single stem.
Ceanothus (Californian lilac) D/ES
All evergreens are tender and the deciduous kinds reasonably hardy.
The evergreen kinds can be, and are often, grown against a wall. It is usual to train a parallel framework to cover the wall, ensuring as always that the lower parts are kept clothed. Prune after flowering, cutting only the young growth hard back to the framework. If treated as free-standing shrubs, they are trained to several leaders and trimmed back to this framework each year, following flowering; winter damage is removed and some thinning may be desirable. Avoid cutting into old wood as this is slow to break.
The deciduous kinds flower on current season’s growth, so to ensure optimum flowering cut all of the previous year’s growths down to ground level, or to a framework, in mid-spring.
Ceratostigma (hardy plumbago) ES
All species are somewhat tender, but though they may be cut back to ground-level in a cold winter they usually break away freely so long as the roots are undamaged. Flowering is on current season’s growth and all growth surviving the winter is cut back to ground-level in mid-spring.
Cercis (Judas tree) DT
It is not easy to train and retain a single leader but this is the best method. Reduce side shoots and gradually remove them. Cercis is generally grown as a shrub, with little pruning. It is, however, important to train in a satisfactory framework and give a light trimming after flowering to remove the immature seed pods. The production of these can be excessive and if left will reduce vigour and extension growth.
Chaenomeles (Japanese or flowering quince) DS
These are spur-bearing shrubs and once regular flowering begins, little pruning is required. Select several leaders and train to a well-balanced framework. An encouragement to help in producing spurs is to cut back all side shoots to three or four buds in the winter months. It is important to keep the centre of the bush open and any shoots intruding should be removed.
If grown as wall shrubs to gain some protection for the flowers, they are best trained fan-wise. All side shoots are shortened and after the spur system has formed no further pruning should be required.
Chimonanthus (winter sweet) DS
Although fully hardy this shrub does not flower freely unless the wood is properly ripened. For this reason, and to obtain some protection for its flowers during the winter, it is usually grown against a wall. Trained fan-wise, the framework is tied to supports, and all branches coming away from the wall are removed. In mid-summer all side branches are cut back to two or three buds of the main framework. In a wet summer any excess growth should be thinned during late summer to encourage better ripening.
Free-standing shrubs are trained to several leaders and all side shoots are shortened back to two or three buds in mid-summer.
Choisya (Mexican orange) ES
This shrub may be damaged in a colder-than-average winter, so plant in a position protected from cold winds. Dead-head after flowering, trimming to shape at the same time.
Cistus (rock rose) ES
All species are tender to some extent, needing full sun and a well-drained, not too rich. Following flowering, remove dead flowers and their stems as well as any winter damage and trim to shape.
If space permits, these climbers can be left to their own devices with a minimum of pruning; most of the species are treated in this way.
They fall more or less into two groups. The first includes those flowering on current season’s growth, e.g. the jackmanii, lanuginosa and viticella groups. These can be cut down to ground-level in late winter.
The second group flowers on short growth from stems produced in the previous year. Included here are the patens, florida and montana groups. These are pruned after flowering, when shoots which have carried flowers are removed and there is a thinning of excess growth. The florida and patens groups sometimes produce a late flush of flowers and such shoots are reduced following flowering.
One or two species such as C. recta and C. heracleaefolia are non-climbers; the former is usually cut to ground-level in late winter whilst the second is cut back to a framework.
For pruning purposes this genus can be divided into those that develop a single stem. The former tend to make clumps and these should be thinned out during the winter when all shoots which have carried fruit can be removed. A number of these shrubs have attractively coloured stems which, instead, are cut to ground-level annually in early spring.
Corylopsis (winter hazel) DS
Flowers are produced during the winter on one-year-old wood. No pruning is necessary unless one wishes to restrict growth, in which case prune after flowering.
Corylus (hazel) DS/T
A few species are tree-like and these are trained to a central leader. Suckering along the trunk is common and these should be rubbed off whilst still soft in late spring. Mostly the species are shrub-like with a strong tendency to sucker; there are trimmed after flowering to restrict them, and the suckers are also removed. C. avellana, the hazel, and C. maxima the filbert or cob, are grown in coppices for their nuts, and C. avellana may be cut down to ground-level every few years for brushwood. Both the hazel and cobnut are grown in gardens for their winter catkins; some trimming is needed following flowering. Both have purple-leaved forms which are pruned quite hard after flowering.
Cotinus (smokebush) ES
C. coggygria and cotinoides may still be better known under their classification of Rhus. If grown for their smoky flowers there is little pruning except to thin out crowded shoots and to tip shoots in the winter months. When growing the purple-leaved forms of either species for autumn colour, hard pruning in the winter months can be practised.
The strongest-growing kinds such as C. frigida can be trained to a single leader to form trees. There are one or two weeping forms such as C. salicifolia which can be trained as weeping standards. A single leader is trained up a stake and all side shoots pinched back until there is a clear 1.8 m (6 ft) stem. Sometimes they are high grafted on to a 1.8 m (6 ft) stem. Cut back all side shoots in mid-spring and train in a well-spaced framework.
Cotoneasters grown as shrubs only require thinning and restriction of growth; evergreens are pruned in mid-spring and the deciduous kinds in winter. The prostrate forms which are used as ground cover benefit from an occasional thinning to let in the light. One or two species such as C. horizontalis, lend themselves to training against an east- or north-facing wall. Form a well-spaced framework, removing any branches which come away from the wall and thinning out the young branches without destroying the grace of the natural habit.
Almost all kinds will form small trees if trained to a single leader; they are, being small in stature, well suited to training as standards. Following training, the only pruning necessary is to remove crossing branches and to carry out thinning during the winter months.
Those to be trained as shrubs can have three leaders. Subsequent pruning consists of keeping the centre of the bush open and carrying out judicious thinning in early spring.
Prune after flowering, cutting back to where new shoots are breaking. Avoid cutting into old wood. At the same time cut out crowded shoots and open up the centre of the bush.
C. battandieri is so different from other brooms that one may be excused for thinking it a different genus. It is slightly tender and often grown against a wall. Either as a wall shrub or free standing, it needs little pruning except for cutting out winter damage in mid-spring. Thin and cut out some of the old wood occasionally.
Daboecia (St Daboec’s heath) ES
Shear over the bushes in mid-spring, taking off old flower stalks and most of the last year’s growth.
In general these shrubs are left unpruned. D. mezereum is an exception for if left unpruned it becomes gaunt with long bare stems. Each spring remove those twigs which have carried the flowers. If the prostrate kinds develop long bare stems, these should be pegged down and covered with soil: they will root and in time, form dense clumps.
Pruning follows flowering, when the shoots which have carried flowers are removed. Open up the centre of the bush and cut out shoots that are crowded.
D. scabra is a strong upright grower and has the added attraction of an interesting bark. Leave unpruned, carrying out judicious thinning only.
Elaeagnus (oleaster) D/ES/T
The strongest growers can be trained as small trees by selecting a single leader. Later pruning is to thin and trim. The less vigorous growers are allowed several leaders and trained as shrubs. Most are grown for their foliage and all benefit from annual pruning. Deciduous kinds should have side shoots cut hard back in March and the centres of the bush kept open. Evergreens should be pruned in mid-spring when they may be thinned and trimmed to shape. As some of the variegated forms have a tendency to revert any plain green shoots should be removed at their point of origin.
Enkianthus (pagola bush) DS
Carry out dead-heading, thinning at the same time.
Erica (heath) ES
Only the European species are commonly grown in gardens and one or two of these are tender. Annual pruning is necessary to keep the clumps tidy, compact and floriferous. Using shears, remove old flowers and most of the previous year’s growth; the winter and spring flowers should be clipped after flowering and the summer and autumn flowers in late winter. Those with coloured foliage can be cut again as the flowers form, for flower and foliage colour do not always blend.
Whilst generally considered to be tender, most, especially the hybrids, will survive all but the coldest winters. Flowering is on current season’s growth. No regular pruning is needed, but to keep the shrub within its allotted space, remove flowered shoots once the blooms have faded.
Only a few species of this large family are sufficiently hardy for cultivation in this country. Failure is most often due to poor siting and planting of specimens that are too large and root-bound. Plant small container-grown specimens in an open site but protected from cold winds. A mass of shoots will be produced on the sapling, but eventually one will develop more strongly to become a leader whilst the remaining side shoots will die away. Later, branches are shed to leave a clean bole.
Eucalyptus has two stages of growth, juvenile and adult; the shape and colour of leaves at each stage may be quite different. Foliage is much in demand by the floral arranger, the juvenile foliage usually being the more popular. Cutting of foliage can take place at any time of the year except when in active growth, but excessive cutting should be avoided during the winter months. When adult shoots are cut the new ones arising will be juvenile and a tree can be kept in this state indefinitely by regular hard pruning in mid- to late spring.
(spindle tree) D/ES/T
A few species will make trees and these are kept to a single leader, the side branches being shortened and gradually removed. The shrubby kinds are allowed several leaders and in general little pruning is necessary to these, except to thin, trim and keep the centre of the bush open.
The deciduous kinds are sometimes grown primarily for their autumn colour and these can be pruned more severely to encourage strong young growth; this is carried out in early spring. The best known evergreen is E. japonicus, of which there are many variegated forms, some of them very prone to reversion. This species, which is grown mainly for its foliage, is trimmed to shape in mid-spring.
Whilst most of this genus is herbaceous, a number are woody. These produce upright, rather succulent stems copiously from a rootstock. After flowering, cut out at ground-level all shoots which have flowered and all weak stems. When growth is not strong, carry out dead-heading, cutting out completely some of the oldest stems.
X Fatshedera lizei (fatheaded Lizzy) ES
This hybrid has a rather sprawling habit and may be trained up a north or east wall or used as ground cover. Grown in this way, pruning is rarely necessary.
Remove dead leaves in mid-spring and cut out any bare gaunt shoots at ground-level.
Hard pruning encourages growth at the expense of flowering so annual pruning should be no more that the removal of crowded shoots from the centre of the bush and a proportion of the oldest wood. When pruning an old or an extra large shrub spread the operation over three years; begin by removing the oldest wood and, as new growth is produced, this can be tipped in early summer.
F. suspensa is often grown against a wall where its long pendulous shoots are displayed to better advantage. A well-spaced fan-shaped framework is trained and tied and from this develop the long weeping branched stems. These are cut hard back to the framework following flowering. When desired as free standing shrubs, several are planted together so as to give each other support. After planting, reduce the shoots by half or even more; the following winter cut back to where they begin to curve over. Once a rigid framework has been formed shoots can be allowed to develop freely; subsequent pruning is to remove some or all of the shoots which have flowered.
Only a few species are hardy enough for cultivation out of doors all the year round and even those can be cut down in a cold winter but the bushes usually break away freely from ground-level. In late spring prune back all one-year shoots almost to ground-level or to a framework.
Garrya (tassel bush) ES
Male and female flowers are produced on different plants and it is the male kind with the long catkins that is grown in gardens. Pruning consists of thinning and trimming to shape in mid-spring.
Pruning is generally unnecessary except to dead-head and trim to shape at the same time.
Griselinia littoralis (broadwood) ES
Generally considered to be hardy except in the coldest districts, although there does seem to be a variation in hardiness amongst different forms. Trim to shape in mid-spring.
(witch hazel) DS
Pruning is generally unnecessary. Most kinds offered for sale are grafted, so watch for suckers; as these closely resemble the desired plant. Remove all shoots coming from below ground-level.
H.japonica arborea will make a small tree if trained to a single leader; shorten the lower shoots but leave them as long as possible.
Hebe (shrubby veronica) ES
A large genus from New Zealand, of varying hardiness, size and form, often as important for foliage as for flowers. A number are tender and should be planted at the foot of a wall. Those that flower early in the year, (for example, H. hulkeana), are pruned after flowering when all shoots which have carried flowers are cut out and there is some trimming. Autumn-flowerers are pruned in late spring when shortening of the shoots is practised and some thinning.
The hardy kinds need little attention except a trimming to shape in mid-spring.
Hedera (ivy) ECI
Ivy comes to mind at once when it is a matter of trying to decide on a climber for a wall. It can, however, be invasive and some claim that it will, if left unattended, dislodge slates and gutters.
Ivy has two stages of growth: the juvenile with angular leaves and climbing roots, and the later stage when side branches without roots are produced, leaves become rounder and flowering takes place. It can be slow to start growing up a wall. Train a well-balanced frame work, paying attention to leaf coverage, especially at the base of the wall. Cut well back from windows, doors, pipes, gutters and the roof. When branching starts, these should be cut hard back to the wall in mid-spring; it is only the young shoots with roots that stick themselves to the wall and once these die there is no hold. Each year cut out some of the oldest wood so that the ivy cover does not become so heavy that it falls away from the wall.
Controversy has long ranged as to whether ivy growing up a tree is harmful to it. As long as the tree is in good health no damage is done.
Mainly a tropical genus; only one of the species, H. syriacus, is commonly seen in modern gardens. This flowers on current season’s growth, and once a frame-work has been trained all young shoots are cut back to within a few buds of it in spring.
(see buckthorn) DS/T
Male and female flowers are born on separate bushes and so to obtain berries they are often planted in groups with one male to four or five females. Though most often grown as shrubs, they make small trees if trained to a single leader with the lower side shoots reduced. Little pruning is required except to trim and thin during the dormant season.
Hydrangeas often take a year or two to settle down before they start to flower regularly. In general they are little pruned except to dead-head and thin out growth in mid-spring.
Climbing hydrangeas attach themselves to their support by means of roots, and as with ivy there are two stages – juvenile growth which clings tight to its support and. When the support has been covered, branching growth with the production of flowers. These flowering shoots are cut back hard in mid-spring.
H. macrophylla, the common hydrangea, flowers on one-year wood and pruning consists of the removal of all, or part of the shoot which has flowered and the cutting out of weak shoots. In wet seasons a more drastic thinning may be necessary to help ripen the wood. The older flower heads are often of interest throughout the winter, and as in cold districts, they give protection to overwintering flowerbuds pruning can be delayed until mid-spring. A few kinds, (e.g. H. paniculate) flower on current season’s growth and these are cut hard back to a framework or to ground-level during early spring.
(St John’s wort) DS
A few species are tender. Flowers are produced on current season’s growth and in mid-spring all shoots are cut to within a few inches of the ground. Larger plants can be produced by thinning and tipping the young growth.
( ) E/DS/T
Hollies are often slow to establish but having done so, grow away strongly. Pruning consists of trimming to shape in spring. Neglected hollies, or those disfigured by the leaf miner pest can be cut back in spring or in summer.
Jasminum (jasmine) E/DCI/S
Some species are tender and need protection. Both the climbers and free-standing shrubs need little pruning except to remove some of the wood which has flowered. This can be carried out after flowering with most, but for those that flower over a long period pruning should be done in spring. J. nudifiorum (winter jasmine) should be pruned after flowering, removing most of the wood that has flowered. This increases flowering and keeps the climber tidier.
Junipers (juniper) EC
Some forms make trees and these should be trained to a central leader, with all side shoots retained. The bushes can have several leaders, but in spring the centres should be cleared of the clutter of shoots, dead and alive. Dwarf and prostrate juniers are not pruned.
(Jew’s mallow) DS
Flowers are produced on the previous year’s growth of bright green stems, so attractive in winter. Kerria has a suckering habit, forming large clumps which may need to be restricted. Cut out old canes at ground-level as flowers fade.
Laburnum (golden chain) DT
Most commonly grown as small trees and often trained as standards, for which they are well suited, although a single leader is to be preferred. Strong vertical shoots tend to appear from low down on the tree and these should be removed as they appear.
Laburnum responds well to spur pruning so that trees can be restricted in size by cutting back side shoots to two or three buds in the winter; they are well suited to pleaching. The trees seed heavily and the immature seed pods should be removed, especially as the seed is poisonous.
Laurus (bay) ES/T
Slightly tender and susceptible to damage from low temperatures or exposure to cold winds. Train to a central leader, retaining all side branches as long as possible. Bays are commonly seen trimmed, an operation which is carried out in mid-spring.
Lavandula (lavander) ES
A few species are tender and need the base of a warm south wall. These are trimmed to shape in the spring, when winter damage is cut out. Common lavender is frequently seen in gardens as an untidy sprawling bush, due entirely to lack of pruning. During spring, just prior to growth commencing, bushes should be clipped hard, in the course of which old flower spikes are removed and most of the previous year’s growth. Neglected bushes need very hard pruning but it is better done in two or three stages and not all at once.
Occasionally it may be necessary to remove at ground-level old wood and any unsightly stems in spring.
Ligustrum (privet) E/DS
Privets are best known asplants though specimens are sometimes used in topiary. Grown for foliage, flowers or fruit they can make handsome shrubs or even small trees. Shrubs are left to develop several leaders and established pruning consists of trimming to shape and thinning in early spring. Strong-growing forms can be trained to a single leader with all side shoots retained but shortened, and eventually removed.
Lonicera (honeysuckle) D/ES/C
Shrubby honeysuckles should, after blossoming, be trimmed to shape and the branches which have flowered should be removed. If a feature is to be made of the berries, pruning should be delayed until the winter, or spring for evergreens.
It is not necessary to prune climbers every year unless space is restricted. Climbers can be separated into two groups; those flowering on current season’s growth are pruned in the winter, when necessary, cutting back hard to a framework; those flowering on one year old wood are pruned after flowering when those shoots which have flowered are removed, together with crowded growth.
Branches tend to be pithy and bark is easily damaged if blunt or badly set tools are used. Pruning is best carried out in summer when new growth is complete; dormant wood is slow to heal and die-back, following winter pruning, is common.
Tree magnolias should be kept to a single leader on which the side shoots are shortened and eventually removed. Young growth is frequently damaged by late frosts and if the leader is destroyed a new one will have to be trained in.
Magnolia grandiflora is still considered as a wall shrub but is really unsuitable in such a position for its large leaves cause undue shading, and with age the trunks become increasingly difficult to keep tied back. Wall-trained M. grandiflora does perhaps flower more abundantly than a free-standing tree so if training is undertaken for this reason a well-spaced framework must be provided. This can be fan-shaped or in tiers, ensuring that the base of the wall is kept clothed. Pruning an established trained shrub involves no more than removing old flower heads and thinning and cutting away shoots coming from the wall in spring.
Bush magnolias need little attention, although dead-heading is desirable for many kinds produce copious quantities of fruit which, if left to develop, reduces vigour. M. X soulangiana varieties have a tendency to produce masses of young growth along the main stem; this should be rubbed off as it appears.
Several of the low-growing kinds can be used for ground cover, which can be kept low and thick if sheared off just above ground-level every three or four years; if not growing strongly remove some of the oldest stems and trim back remaining growth. Other forms need only occasional pruning when the oldest stems are cut out at ground-level in the spring.
Malus (crab apple) DT
Some species are raised from seed and therefore on their own roots, but many species and all modern varieties are grafted on to one of the fruit rootstocks which controls the ultimate size of the tree. Most crab apples are trained as standards although they can also be trained to a central leader. Once the framework has formed, there is little pruning required beyond the removal of crossing branches.
Olearia (daisy bush) ES/T
Most species are tender and are often planted as free-standing shrubs at the foot of a wall. O. haastii and O. macrodonta are two of the hardiest species, needing no protection. Those which flower early in the year are pruned after flowering when old flower shoots are removed and the bush is trimmed to shape. Those flowering late are pruned towards the end of spring or early summer; again old flower stalks are removed and bushes are trimmed to shape.
Most species are tender and need wall protection. O. delavayi and O. heterophyllus are the hardiest, the former flowering in spring, the latter in late autumn. The early flowers are trimmed after flowering, the late flowers at the end of spring just before growth begins.
Paeonia (tree peony) DS
Most species are herbaceous, only a few having woody stems.
Occasionally take out some of the old stems at ground-level if they become gaunt; remove dead flowers and fruiting heads after flowering; if seeds are wanted, delay until these have been shed. Towards the end of a wet summer some thinning of lush growth will aid the ripening of wood.
Parrotia (Persian ironwood) DS/T
A shrub grown for its early flowers and colourful bark, but particularly for its gorgeous autumn colour. A strong-growing shrub with tiered branches which can become tree-like. It can be trained to a central leader with all side shoots retained, or it can be allowed to develop naturally.Parrotia persica produces masses of branches which should be thinned in winter or following flowering. Cut back to a point where there is another branch.
This genus includes the Virginia creeper. All are vigorous climbers which attach themselves to supports by means of tendrils on which there are suckers. Unless given plenty of space (as on an old tree) they can be invasive, shutting out light from windows. Contrary to popular belief, these climbers do not dislodge slates, gutters and down-pipes; they merely cling on to the cladding. If desired, (and where possible), cut out old wood in winter.
Passiflora (passion flower) D/EC
All species are tender and even P. caerulea, the hardiest, can be damaged by winter cold. Train a well-spaced framework to cover a wall, then thin out crowded growth and drastically reduce during late spring.
Pernettya (prickly heath) ES
A suckering shrub grown for its attractive show of fruits which remain largely untouched by birds. In good conditions it can become rather invasive and some restriction may be desirable; otherwise occasionally remove some of the oldest wood in spring.
Philadelphia (mock orange) DS
If there is plenty of space, these shrubs can be grown with the minimum of pruning, removing blind shoots. When space is limited, remove branches that have carried flowers and thin out surplus shoots in summer.
Only some species are woody and most of these are slightly tender, needing full sun and warm position. Cut out or cut back old flowering stems and thin growth in spring.
All species are somewhat tender and are often grown on a south wall. Valued more for their young red foliage than for their flowers which are not very interesting. In mid-spring all growth is trimmed back to about half of that produced in the previous year.
Little pruning is necessary except to dead-head, thin and trim. Young non-flowering growth of P. forrestii is a brilliant red which fades to green as it ages. A second flush of brilliant growth can be obtained by the (unorthodox) practice of trimming back the shoots when the leaves have turned green.
Most species are tender, P. tenuifolium being the hardiest of them. Plant in a protected place out of cold winds. Trim to shape in mid-spring, cutting out winter damage and thinning.
P. baldschuanicum, (the Russian vine), is commonly grown for screening. Its rampant habit makes it ideal for this purpose but unless there is plenty of space its nature can be an embarrassment. Each year, in early spring, remove shoots that are likely to encroach, drastically reduce and thin out, cutting as near to the ground as possible.
Untidy growers that tend to collect dead leaves and accumulate a mass of dead or blind twigs. Clear out centres of bushes in early spring and reduce the previous year’s growth by a half.
There are many kinds of prunus of differing size, shape and habit, and all of them susceptible to silver leaf disease. Pruning of most species is kept to a minimum after building up a framework. Those which make trees are trained to a central leader.
Japanese cherries are grafted, sometimes low down but most often on to stems of varying lengths. Heads are often one-sided and by judicious pruning this should be corrected so as to produce a well-spaced and balanced spread.
Ornamental peaches, almonds and their hybrids should have a portion of wood which has flowered removed in spring. Sometimes they are fan-trained against a wall; after building up a framework, remove shoots which have flowered. Prunus triloba, glandulosa and their forms are also grown against walls, and following the completion of a well-spaced frame-work, all side shoots are cut hard back to this after flowering.
Some kinds, (such as P. serrula), are grown for their barks. Train a central leader and expose the trunk as soon as possible. There are a number of weeping forms of cherries of various species. These may be low grafted but are most often grafted high. Support the main stem with a stake and ensure that there is a sufficient length of trunk to allow the pendant branches to hang gracefully. If the main stem is not long enough train in a leader, reducing the framework until sufficient length has been gained, then train in a new frame-work.
The evergreen species are most often grown as hedges though they can be grown as specimen plants. Keep to a single leader, retaining side shoots, and trim to shape in spring.
Pyracantha () ES
Best grown against a north or east wall, for which its habit is well suited. During training select several leaders, spacing them apart to allow side branches to cover their allotted space without overcrowding. The main leaders should be secured in position, for though they keep close to the wall they tend to fall away with age. During mid-spring, cut back any shoots coming away from the wall, thin out crowded shoots and trim back. As the leaders become old, select and train in new ones; when these are established the old can be removed.
Pyracanthas are perfectly well suited for growing as free-standing shrubs; three or five leaders should be selected and well spaced. In mid-spring open up the centre of the bush, thin out crowded shoots and trim to shape.
Pyrus (pear) DT
Train to a single leader. No regular pruning is necessary beyond the removal of crossing branches. P. salicifolia, and especially its weeping form, need to have the leader secured to a stake and should be trained to a 2.4 m (8 ft) stem before a framework is allowed to develop.
Azaleas, which form a series among the rhododendron species, are included here. Many hybrids and some species are grafted and any suckers which arise from the rootstock should be removed as they appear; if left they grow away at the expense of the plant. Carry out dead-heading annually and at the same time trim back any shoot growing out of alignment. With age, some rhododendrons become too tall, bare at the base, or their shape falls away; these can be cut back really hard after flowering.
Bud blast is a disease which kills the flower buds; remove and burn infected buds.
Gardeners are warned that some species can cause a skin rash. When pruning any species of Rhus, wear thick gloves, cover all bare parts of the body and wear overalls.
Tree forms are kept to a single leader and feathered. Shrubs can be left unpruned, thinning out crowded shoots in early spring. R. typhina and glabra and their forms are usually grown mainly for their foliage, either summer or autumn; the amount and size can be increased by pruning in the winter.
Ribes (currants) D/ES
A few species are tender. Mostly they flower on one-year-old wood, and after flowering the shoots which have borne flowers are removed. Some form spurs and a framework should be formed on a short leg, and well spaced. During the winter open up the centre of the bush and cut back young growth to within two or three buds of the main stems. Evergreen kinds are little pruned except to thin, if required, in spring.
Rubus (brambles) D/ES
A few of the evergreen species are tender and need wall protection. Most species have a stool-like or even suckering habit, but some of the deciduous kinds have canes of only two years’ duration.
Brambles with coloured stems are cut to ground-level in early spring, and young growth drastically thinned out in established clumps. Species grown for their flowers or fruit are pruned during the winter. If stems are of two-year duration only, those shoots which have flowered are removed; if stems are longer lived, those which have flowered should be cut back.
Ruta (rue) ES
All species are slightly tender and likely to be damaged in a cold winter. All are short lived and replacements should be kept available for replanting. Common rue (R. graveolens) is an untidy grower and needs drastic thinning in late spring.
Salix (willow) DS/T
Willows vary from tiny shrubs to large trees, all liking a moist soil.
Strong-growing kinds are trained to a single leader; smaller kinds can be similarly treated but with all side shoots retained although reduced.
There is a tendency for branches to be damaged or lost in gales so space out the main branches; prevent undue extension and avoid narrow crotches.
Shrubs can be treated as already described or can be allowed several leaders. When willows are grown specially for catkins or foliage, best produced on young wood, cut hard back to within a few inches of the base of the previous year’s growth, just before growth commences. When grown for their coloured stems, cut to ground-level or within a few buds of a framework in early spring. Small growing and prostrate kinds are rarely pruned except to remove dead wood or to thin.
Santolina (lavender cotton) ES
Fragrant shrub with grey-white leaves, grown for its foliage rather than its yellow flowers which, however, do have some attraction. Unpruned bushes sprawl untidily and are short lived. After flowering, the old flower stems should be removed and the bushes trimmed back. When growing just for foliage, trimming is carried out in mid-spring and most of the previous year’s growth is removed; a second trimming is desirable as the flower buds appear.
Sarcococca (Christmas box) ES
Restrict if clumps become invasive; otherwise just cut out old gaunt stems, or if clumps become untidy shear back to within a few inches of ground-level in spring.
Many species are tender and need protection of a wall; in late spring remove winter damage and thin out crowded shoots. Free-standing shrubs are similarly treated earlier, when they are trimmed to shape, thinned, and old flower stalks removed.
Occasionally remove some of the oldest wood and if necessary trim to shape in spring.
Spartium (Spanish broom) LS
Its pithy stems tend to be soft and easily damaged if growing in shade or a rich soil. Trim shoots hard back to a framework in spring.
Some species flower on one-year wood, e.g. S. X vanhouttei and X arguta; these are cut back to where new growth is developing following flowering. Others such as S. X bumalda, S. japonica and S. douglasii flower on current season’s growth and are pruned to within a few inches of ground-level during late winter.
Symphoricarpos (snowberry) DS
All species have a suckering habit which can be invasive in a good soil; if so, clumps must be restricted. During early spring, remove the oldest and weakest shoots, thinning the remainder.
Syringa (lilac) DS/T
If space is not limited, little pruning is required except for dead-heading and the removal of blind shoots from the centre of bushes. In small gardens there should be a reduction of some of the shoots and some trimming following dead-heading.
The stronger kinds will make small trees if trained and kept to a single leader; this needs regular attention because of the forking habit of lilac. Most cultivars of lilac are grafted either on to privet or wild lilac; suckers from the former stock are easy to recognise but those of the latter are not, therefore any shoot which emerges from beneath ground-level should be removed at the point of origin.
Tamarix (tamarisk) DS/T
Some flower on one-year-old wood and these should be pruned following flowering, the wood which has flowered being removed and the resulting growths thinned. Others flower in late summer or autumn and these are pruned hard in March, being cut back to a framework; some thinning of resulting growth is desirable. The strongest kinds can be trained into small trees by selecting a central leader and reducing side shoots.
Thymus (thyme) ES
The mat types may need occasional attention to remove dead wood, but if this becomes excessive the entire planting should be lifted and renewed. Those forming shrubs, (e.g. the common thyme T. vulgaris) are pruned in mid-spring when there is a thinning of shoots and most of the previous year’s growth is trimmed back.
A few species are tender and need wall protection. Some of the winter flowerers also need protection for their flowers. Little pruning is necessary but occasionally some of the oldest wood is removed and it may be desirable to trim to shape following a heavy fruit set. Winter flowerers are pruned in mid to late spring; summer flowerers are cut in late winter or early spring, and evergreens are trimmed in mid-spring.
Vitis (ornamental vine) DCI
If growing over a tree, no pruning is required. If on a wall, fence or pergola where space is limited, after training in several rods all side shoots are cut back to one or two buds of these in the winter. Do not delay pruning otherwise bleeding will occur.
A very popular and beautiful shrub that is too often planted where there is insufficient space or where no attention is given to pruning. All species are vigorous and if left to their own devices their long trails can dislodge slates, gutter and down-pipes. Following planting, cut back stems by half, and continue to do this each spring until a well-spaced framework has been trained in. In mid-summer all young shoots are cut back to four or five buds, and in winter these shoots are reduced to two or three buds. This builds up a spur system and reduces extension growth, so encouraging the greatest number of flowers.