April pruning of trees, shrubs and
climbers
Many shrubs, trees and climbers are showing signs of growth and so it is an ideal time to check them over for winter damage. If you feel they need a little care and attention, here are a few notes to use as a pruning guide during April. You will find timely advice on Abutilon, Acacia, Aucuba, Bupleurum, Callicarpa, Camellia, Calluna, Caryopteris, Ceanothus, Ceratostigma, Cistus, Clerodendrum, Convolvulus, Corylopsis, Cotoneaster, Eccremocarpus, Erica, Euonymus, Exochorda, Fatsia, Forsythia, Hebe, Hydrangea, Hypericum, Kerria, Lavandula, Leycesteria, Ligustrum, Lonicera, Magnolia, Olearia, Osmanthus, Passiflora, Paulownia, Perovskia, Phlomis, Photinia, Pieris, Pittosporum, Potentilla, Romneya, Salvia and Solanum. It's also not too late to complete March pruning jobs if you haven't got round to completing them yet.
TREES
Acacia dealbata (mimosa)
Young trees can be encouraged to produce compact and well-branched heads by pruning sideshoots on the main stems after flowering to two or three buds. Thereafter, established acacia trees do not need routine pruning other than the removal of frost-damaged growth. This is best carried out after flowering during late spring. Where space is limited, established mimosa trees can be restricted in size by cutting back by up to one-third their height at this time of the year. However, other acacias do not respond well to hard pruning.
Magnolia grandiflora (summer flowering bull bay)
Established specimen trees require no routine pruning, other than the removal of dead, crossing or diseased branches. Wall-trained specimens should have wayward shoots, that are growing away from the support, removed in spring.
Paulownia (foxglove tree)
Specimen trees require no routine pruning, other than the removal of dead, crossing or diseased branches. Paulownias can also be trained to produce extra large foliage by cutting all new growth back hard to a stubby framework during April. New growth will produce tropical-looking leaves but no flowers.
SHRUBS
Abutilon megapotamicum
If you are lucky enough to be able to grow this slightly tender abutilon outdoors, when plants start to put on new growth in spring, it is easier to see the extent of the winter damage. Use a pair of secateurs to remove any frost-damaged shoots. If you want to get the best foliage displays from variegated varieties, cut back all shoots hard to a stubby framework near to the ground. If this is too drastic for you reduce all stems by about one-third. All varieties can be kept within bounds in this way.
Aucuba japonica (spotted laurel)
It’s the ideal time to prune female forms of this popular, hardy, rounded evergreen, now that the winter display of berries is over. During the first spring after planting, cut back growth by about one-third to encourage bushy growth from the base. Thereafter, most plants will produce a neat, rounded shrub without the need for pruning, but they also respond well to hard pruning to keep them compact and within bounds. Neglected plants can be cut back to a woody framework 60-90cm in height. If this is too drastic for you, cut back one-in-three stems starting with the oldest so that the whole plant is rejuvenated over a three-year period. Wait until midsummer to trim spotted laurels grown as hedges.
Bupleurum
Little or no annual pruning is needed, other than the removal of dead or diseased stems and thinning out congested growth. Old and neglected plants can be rejuvenated by cutting back hard to a stubby framework of stems 5-15cm from the ground. If this is too drastic for you, cut out one-in-three stems starting with the oldest so that the whole plant is rejuvenated over a three-year period.
Callicarpa (beauty bush)
Don’t prune the beauty bush until the danger of frost has passed in your garden, but before new shoots start to break. Although no annual pruning is needed, other than the removal of dead or diseased stems and thinning out congested growth, established plants can become lop-sided with age and may benefit from a little judicious pruning. Simply cut back wayward stems to a younger sideshoot lower down or remove completely. Old and neglected specimens can be rejuvenated over a five-year period by cutting back one-in-five of the stems each April, starting with the oldest.
Camellia
Although camellias require little or no annual pruning, they can be cut back in spring after flowering to tidy up straggly stems. You can also keep bushes small and compact by cutting back the previous year’s growth to within a couple of buds of the old growth. Old and neglected plants can be cut back hard in spring to encourage vigorous new shoots from the base. Even substantial branches can be reduced to a stubby framework 60-90cm high. If this is too drastic for you cut out one-in-three stems instead, starting with the oldest, to get a rejuvenated plant within three years. Keep all plants looking their best by removing faded flowers that remain on the shrub.
Calluna (Scotch heather)
Keep plants neat and tidy by trimming with shears after flowering is over but before new growth breaks. Cut back to just below the old flower-spike. This is also an ideal time to remove any uncharacteristic growth and straggly shoots as well as any dead stems. Old and neglected plants do not respond to drastic pruning and so are best replaced.
Caryopteris (blue spiraea)
To keep this shrub neat, fresh looking and flowering well, cut back all the previous year’s growth to a stubby framework about 5cm from the ground. Remove weak shoots altogether.
Ceanothus (evergreen types)
Summer-flowering evergreen ceanothus, such as ‘Autumnal Blue’ and ‘Burkwoodii’, that bloom on growth produced the previous year, need to be pruned lightly each year during April to keep them within bounds. Do not cut back into old wood, since this is unlikely to re-sprout. If a plant gets old and neglected or too big for its position, you’d be better off replacing it.
Ceratostigma
During the first spring after planting, prune back the new stems to within 5cm of the previous season’s growth. This will encourage lots of new sideshoots low down of the shrub. Once established, remove any dead or damaged stems and cut the remainder back to 5cm. This will keep the plants neat and low growing. In colder areas, the top-growth might be killed in harsh winters and this should be removed before new shoots are produced from below ground.
Cistus (rock rose)
During the first spring after planting, pinch out the main stems to encourage a bushy habit. Thereafter, little or no regular pruning is required, other than the removal of dead or frost-damaged shoots as well as any uncharacteristic or straggly growth. Old or neglected plants are best replaced, since rock roses do not respond well to severe pruning.
Clerodendrum bungei
This borderline hardy shrub is often damaged in winter by severe frost. At this time of the year, inspect the shrub and cut out any frost-damaged stems. In sheltered gardens where there is little damage, cut out one-in-three stems starting with the oldest each year to keep the shrub neat and vigorous. Alternatively, cut all shoots to a stubby framework 30cm high.
Convolvulus cneorum
A mound-forming evergreen shrub that needs no routine pruning other than the removal of uncharacteristic shoots that disfigure its overall shape and appearance. These are best removed completely or cut back to a sideshoot lower down, before buds break in early spring.
Corylopsis
The best advice is leave well alone unless you are running out of space. In this case, cut back old or weak stems completely, immediately after flowering to avoid spoiling the overall shape of this decorative deciduous shrub.
Cotoneaster (evergreen types)
Shrub-forming evergreen or semi-evergreen cotoneasters, such as Cotoneaster x watereri, C. ‘Cornubia’, C. frigidus and C. salicifolius, require little or no annual pruning, other than the removal of dead or diseased stems and thinning out congested growth to near ground level. This is best done during April. Overly long or wayward shoots can be shortened at the same time. You can restrict the shrub’s overall size in this way by cutting back selected stems each year. Neglected plants will respond well to hard pruning and so can have all stems cut back to near ground level. If this is too drastic for you, cut out one-in-three stems, starting with the oldest instead.
Erica carnea (winter heath)
Annual pruning helps keep plants neat and tidy. Trim with shears after flowering is over but before new growth breaks. Cut back to just below the old flower-spikes. This is also an ideal time to remove any uncharacteristic growth and straggly shoots as well as any dead stems. Old and neglected plants do not respond to drastic pruning and so are best replaced.
Euonymus japonicus
During the first spring after planting, cut back the current season’s growth by about one-third to encourage a bushy shape. No other routine pruning is required, other than the removal of dead stems. Hedges should be pruned in April to maintain a neat shape. Use secateurs rather than shears or a hedge trimmer to avoid damaging the leaves that remain on the plant after it is trimmed.
Exochorda
New plants can become a thicket of spindly stems, so these are worth thinning after flowering to prevent overcrowding later on. Established plants can be kept compact and flowering well by pruning out one-in-three stems each spring after flowering, starting with the oldest. Old and neglected plants respond well to severe pruning and can be cut back hard at this time of the year, although you will loose the flowering display during the current season.
Fatsia japonica (false castor oil plant)
Little pruning is required if there is plenty of room for this large, architectural evergreen shrub to spread. However, if space is limited it can be kept within bounds by pruning one-in-three stems back to their base during April, starting with the oldest. Cut back whole straggly branches, rather than shortening all when trying to limit its spread, otherwise you risk upsetting the plants naturally graceful habit.
Forsythia
Forsythia is still flowering well into April in many parts of the country, so pruning will still need to be carried out. Do not prune forsythia during the first few years after planting. However, once established, older plants that are left un-pruned become woody at the base where few flowers are produced. To avoid this, prune after flowering has finished, by cutting out one-in-three of the main stems at the base, starting with the oldest. Neglected plants can be rejuvenated by cutting back all flowered shoots to a strong bud near to the base of the shrub. New wall-trained shrubs should have stems tied into the supports to form a permanent framework. Thereafter, new growth should be cut back after flowering during early spring to two or three buds from the main framework. Trim forsythia hedges after flowering too, then leave un-pruned until the following year otherwise you risk removing all of next spring’s flowers.
Hebe
Hebes, such as Hebe speciosa, H. macrantha and H. salicifolia, can be damaged by cold winds and low temperatures in winter. Although they require little routine pruning, it is worth removing any dead or frost-damaged growth in April. Well-established shrubs that are outgrowing their allotted space can be reduced in size by cutting back overly long stems to a new sideshoot lower down. Large-leaved hebes grown for their flowers, such as ‘Autumn Beauty’, ‘Midsummer Beauty’, ‘Great Orme’ and ‘Marjorie’ can be kept neat and flowering well by pruning now. Cut back all stems to within 15cm of ground level every other year or, if this is too drastic for you, and on older plants which may not take kindly to such hard pruning, cut back one-in-three stems starting with the oldest. Variegated hebes that produce all-green reverted shoots, should have these pruned out completely.
Hydrangea (mop-head types)
Leave the attractive, large, papery flower heads on Hydrangeas macrophylla and H. serrata varieties until the worst of the winter weather is over to protect the stems underneath. Then, during April, cut off the flower heads with a short piece of stem – cutting back to the topmost pair of plump buds. Little or no other pruning is required with well-established specimens, other than the removal of dead or damaged stems. However, it is worth pruning back overly long stems to improve the shrub’s overall shape as well as any weak growth. Old and neglected plants can be cut back hard at this time of year, but you will loose out on the flowering display during the summer. Another option is to rejuvenate the plant over a three-year period by cutting back one-in-three stems each year starting with the oldest.
Hypericum
Popular varieties of hypericum such as ‘Hidcote’ and ‘Rowallane’ can be pruned now, along with Hypericum forrestii and H. beanii. Keep plants neat and compact by removing any weak, dead and damaged growth, then cutting back all remaining stems to near ground level or to a sideshoot lower down. If you find this is too drastic, cut back one-in-three stems instead, starting with the oldest. Old and neglected plants can be rejuvenated in the same way.
Kerria
Prune after flowering by removing one-in-three stems to near ground level. Prominent specimen plants can be improved further by cutting back half of the remaining flowered stems by one-third to half their length to encourage the production of vigorous new flowering shoots at different heights. All-green reverted shoots on variegated varieties should be cut out completely.
Lavandula
During the first spring after planting, when you can see new shoots breaking at the base, cut back the previous year’s growth to within 5cm of older wood to leave several buds to break and produce a bushy plant. Regular annual pruning is then required to prevent the plant sprawling as well as becoming woody at the base as it matures. Simply trim during spring as new growth starts, cutting back most of the previous year’s growth. Old and neglected plants do not respond to severe pruning and so are best replaced. However, if there are sideshoots low down on larger stems, you can try cutting these back to just above the sideshoot to reduce the overall size of the plant. Lavender hedges are best clipped into shape at this time of the year too.
Leycesteria
During the first spring after planting, cut back all stems to within 5-10cm of the ground to produce a neat clump. To keep an established shrub tidy and flowering well, cut out one-in-three stems each year starting with the oldest. Alternatively, since all flowers are produced on the stems produced during the current season you can cut back all the previous year’s shoots that have flowered. Similarly, old and neglected plants respond well to severe pruning and can be pruned back hard at this time of the year by cutting all stems to near ground level.
Ligustrum (privet)
During the first spring after planting, cut back all stems of upright-growing varieties by about one-third to encourage sideshoots to form low down on the plant and thereby produce a bushy, well-balanced shrub. Repeat this process annually if you are growing privet as a hedge until it reaches the desired height. However leave trimming established hedges until May and trim again in September. Well-established, specimen privet shrubs require little pruning, other than the removal of dead or damaged stems as well as all-green reverted shoots on variegated varieties. Cut these back to their point of origin. Old and neglected plants that have become sparse and woody at the base respond to severe pruning at this time of the year. Cut back all stems to within 10-15cm of the ground or, if you find this too drastic, prune back one-in-three stems each year over a three-year period starting with the oldest.
Lonicera (winter-flowering varieties)
Lonicera varieties that produce winter flowers on bare stems, such as Lonicera fragrantissima and L. x purpusii can be pruned now to keep them within bounds. Established specimens require little or no pruning other than the removal of dead, damaged or weak growth. If the shrub is congested or needs reducing in size, cut out one-in-three stems starting with the oldest. Try to cut back to a sideshoot low down on the plant and aim to maintain the overall shape and balance to the outline of the shrub. Old and neglected plants can be treated in the same way or have all stems cut back to a stubby framework during the dormant season.
Olearia (daisy bush)
During the first spring after planting, cut back vigorous stems to encourage sideshoots and a bushy habit. Thereafter, keep pruning to a minimum by simply removing any dead, damaged or weak shoots at this time of the year. You can also lightly trim back any branches that spoil the symmetry of the plant. If a plant outgrows its allotted space, cut back all the previous season’s growth by about one-third to restrict its size. Old and neglected plants can be cut back hard at this time of year. However, if this is too drastic for you, rejuvenate the plant over a three-year period by cutting back one-in-three stems each year starting with the oldest.
Osmanthus
Little or no routine annual pruning is required, other than the removal of dead, damaged or weak stems. Established plants can be kept in shape by cutting back uncharacteristic or overly long shoots. Old and neglected plants respond well to severe pruning and can be cut back hard at this time of year. However, if this is too drastic for you, rejuvenate the plant over a three-year period by cutting back one-in-three stems each year starting with the oldest.
Perovskia
It is now safe to remove all the previous year’s stem’s that have provided protection during the winter months. During the first spring after planting, cut back all stems to a few buds from the ground as soon as new shoots start to break. Thereafter, cut back annually at this time of the year to a stubby framework, pruning to two or three buds. Old and neglected plants can be treated in the same way.
Phlomis (Jerusalem sage)
During the first spring after planting, cut back the previous year’s growth to within 5cm of older wood to leave several new shoots to produce a bushy plant. This will encourage a neat, bushy habit. Thereafter, little or no routine pruning is required, other than the removal of frost-damaged or weak growth. However, if a shrub starts to become lop-sided, cut back the offending stem to a plump bud lower down within the bush so that the cuts cannot be seen. Although old and neglected plants respond well to severe pruning and can be cut back hard at this time of year, they relatively short-lived plants so are probably best replaced.
Photinia x fraseri ‘Red Robin’
During the first spring after planting, cut back the main stems by about one-third to encourage sideshoots and a bushy habit. Thereafter, little or no routine pruning is required, other than the removal of dead, damaged or weak growth. Once the bright red new foliage display begins to fade, clip hedges and repeat in midsummer.
Pieris
Little or no routine pruning is required, other than the removal frost-damaged or weak growth. Deadhead after flowering and cut back any wayward or straggly shoots that spoil the compact shape.
Pittosporum
During the first spring after planting, cut back the main stems by about one-third to encourage sideshoots and a bushy habit. Thereafter, little or no routine pruning is required, other than the removal of dead, damaged or weak growth. However, you can clip with shears at this time of the year to remove wayward shoots and neaten the shrub’s overall shape. All-green reverted shoots on variegated varieties should be removed completely. Old and neglected plants respond well to severe pruning and can be cut back hard at this time of year. Trim established hedges annually during April and again in May.
Potentilla (shrubby cinquefoil)
Keep plants neat and vigorous by cutting back all the previous year’s growth by about one-third using shears. A dome of fresh new growth will be produced as well as plenty of flowers. Old and neglected plants respond well to severe pruning and can be cut back hard to a stubby framework of stems at this time of year.
Romneya (Californian tree poppy)
Now that the worst of cold weather is behind us, Californian tree poppies can be cut back, removing all damaged stems. Either cut back to live growth lower down or reduce to near ground level.
Salvia microphylla
Shrubs grown in mild areas or at the base of a sheltered wall or fence elsewhere can survive the winter and need to be tidied up by removing any frost-damaged shoots. Cut the remaining stems back to a stubby framework. If a plant survives long enough to become old and neglected it is best replaced with a new one.
CLIMBERS
Eccremocarpus scaber (Chilean glory flower)
During the first spring after planting, cut back all new growth to 15cm to encourage new shoots from the base. This tendril-producing climber flowers on new growth, so in subsequent years, cut back all frost-damaged growth and then reduce other stems to about 60cm. The new climbing stems will carry the colourful trumpet flowers.
Passiflora (passion flower)
The best way to grow passion flowers is to establish a permanent framework of stems spaced about 15-20cm apart on a sturdy support, such as pergola or arch, or as a fan-trained specimen against a wall or fence. During the first spring after planting, select the strongest shoots to tie into the support. If growing the climber up a post to subsequently cover the top of a pergola, remove any sideshoots that develop until the stems have reached the required height. Each spring, remove any frost-damaged growth completely on well-established plants, then cut back new growth to within 15cm of the established framework. After flowering in late summer, cut back flowered shoots to within 2 or 3 buds of the framework. Neglected plants can be reinvigorated now by cutting back one-in-three of the oldest stems to a new sideshoot near the base.
Solanum (potato vine)
Established plants should be pruned each year during early spring to thin out overcrowded growth and restrict the size of the climber. Aim to create a framework of well-spaced branches over the support. Once well-established, cut back shoots not needed to extend the framework to two or three buds of their base. Neglected plants can be tricky to rejuvenate because they do not respond to severe pruning. Instead, cut out one-stem-in-three from the framework, starting with the oldest, every other year. Ideally cut back to a newer sideshoot lower down, or cut right back to the base if no suitable shoots exist.
