Pruning trees and shrubs in the garden.

Pruning is undertaken to control growth, define shape, create flowering/fruiting branches for the following season, improve air circulation around the plant, reducing the chance of infection and probably most importantly to remove dead, damaged or diseased areas of a plant.

Spring-flowering shrubs should be pruned in late June, after flowering. Prune large shrubs quite hard, younger plants should have just the weakest growth cut back.

August is perhaps the best month for pruning, when the growth of most plants starts to slow. Pruning in August gives the plant a chance to callous over before the drop in temperature in autumn. Otherwise, prune deciduous shrubs when they are dormant in the winter and evergreen shrubs in spring, but the best rule of thumb is to prune shrubs just after they have finished flowering.

Traditionally, and you'll find it mentioned in old gardening books, when pruning trees, any new cuts larger than about 3 inches, were painted with pruning paint (such as Arbrex). The application was to seal the fresh cut to reduce the chance of infection and insect attack. However, the consensus now is that pruning at the correct time of year and leaving the cut to naturally heal over is preferable.

 

Table: A list of plants and shrubs and how and when to prune them .
Plant What to do When to prune
Acer Prune in the winter, whilst the trees are dormant, else they have a tendency to bleed. Winter
Box Shape box hedging in the spring. Spray the hedge lightly with water first to reduce the amount of sap sticking to the shears. Spring
Buddleia davidii Left unpruned buddleias produce fewer and smaller flowers. They flower on new growth so it's best to prune in late Feb or early March before new shoots develop on existing stems. Cut all stems down to 30cm (12in), if you want to have a taller bush at the back of a border or to add more structure to the bed, leave the stems a bit longer 45-60cm (18-24ins). Early spring
Camellia Dead head and prune after flowering in the spring. Spring
Clematis (spring flowering incl. alpina and macropetala) They flower on last year's growth, but they can get a bit boisterous so tidy up after flowering, rather than extensive pruning. Late spring
Dogwood (Cornus), hazel (Corylus) and willow (Salix) that are grown for winter stem colour

In late autumn/early winter, prune to restrict the height and width of their growth.

They respond really well to coppicing so every 2-3 years, remove all the growth above a couple of inches from the ground in Feb-March. This will encourage lots of fresh vigorous growth from the base of the plant. The following winter you'll have multiple stems with some lovely winter colours.

Winter
Fuchsias Prune hardy fuchsias hard in early spring. New shoots appear at the base of the plant. Early spring
Heather Prune to the base of a flowering stem. Spring
Hydrangea (mophead and lacecap) They don't require pruning, but may need to be tidied up, or their size reduced and or restricted.

Mophead hydrangeas produce flowers from buds that formed in the previous summer. The old flower heads give frost protection to these new buds, so the plant shouldn't be pruned until all danger of frost has passed, typically this is mid to late May. Cut growth back to just above a pair of buds.

Lacecaps are hardier, so can be pruned after flowering, in the autumn.

May
Lavender Cut and shape with shears after flowering has finished, usually by the end of August. Don't cut too much into old wood as they only produce shoots from new growth. August
Magnolia Magnolia's don't like being pruned. Where branches are removed, you tend to either get dieback or lots of new shoots growing. However dead or diseased branches should be removed or if the tree looks unbalanced. The best time to do this is in July to August. Mid summer
Oranmental grasses Don't cut back, wait until spring then remove any dead growth. Spring
Philadelphus (mock orange) After flowering, cut back the stems that have produced flowers, cut these back to new growth lower down. Overgrown philadelphus should have a third of the shrub cut down to just above ground level in spring, repeat this over the following two years. Late spring
Pyracantha Pyracantha flower on the previous years growth, so any pruning is likely to reduce the amount of berries you'll get later in the year. The best time to prune is hard in March, cutting new growth back to 10 cm in July and October. March
Rose

Most roses flower on new growth. In March, with shears or secateurs, as well as removing dead, diseased and crossing stems, also prune to shape and to let light and air into the centre of the plant.

Miniature roses: Only remove dead and or diseased growth, trim to shape and deadhead. Use scissors, as using your hand or secateurs may damage the plant.

Don't prune
Wisteria Prune wisteria twice a year, in February and July, cutting back to 7 spurs in Feb and 2 spurs from the main stem in July (hence 7 in 2 and 2 in 7). The July pruning exposes the wood to the sun, which then bear next years flowers, cut back to 9in of old wood and tie any laterals in horizontally. Beware that the sap can stain clothing. February
Table: A list of fruit plants and shrubs and how and when to prune them.
Fruit What to do When to prune
Apple and pear

The best time to prune is in Jan-Feb when the trees are dormant. First remove any dead, diseased or dying branches, including any that are showing signs of canker, then remove any that are crossing or rubbing.

Remove congested branches from the centre of the tree, leaving 4 to 6 of the strongest branches, to try and create a goblet shape, this lets air into the centre encouraging a healthy tree and reducing disease.

Reduce the length of the remaining branches by removing a third of last season's growth. Prune any shoots from the main branches to 6in (15cm) in length, leaving 6-8 flower buds, from which the fruit should form.

Summer prune fan or espalier trees in late July to force the plants energy into the fruit. Prune side shoots to two or three buds.

Remove suckers growing around the base of apple and pear trees. These are from the rootstock the apple or pear trees are grafted onto, sending up new shoots.

Winter
Apricot They require very little pruning. Remove dead, damaged and diseased branches in the spring and thin and train branches in the summer. Mid summer
Blackberry Blackberries fruit on last seasons growth, prune out fruiting branches after fruit has been picked, remove all but the the 6 strongest new branches, tying these to supports for next year's fruit. September
Blackcurrant Blackcurrants fruit on newer growth. On two year and older bushes, cut a third of the oldest stems (these should be blacker than the new growth which is a pale brown colour) to a couple of inches above ground level from late autumn into winter. Another method of pruning is to cut the stems of fruit bearing branches at harvest time (August), you can then collect the fruit more easily, although this might reduce the size of the crop in subsequent years. September
Damson Pruning won't improve the crop. If you have branches that are in the way of other plants or give the tree an unbalanced look, remove them, but otherwise just remove dead or diseased branches. Pruning is best left until late June or July to reduce the chance of excessive 'bleeding'. Mid summer
Fig (Ficus carica) Prune trees in April just before they start to start growing. Remove dead, diseased and crossing branches. Also prune as hard as necessary to restrict size, but bear in mind that the 'fruit' forms in the previous year on that seasons growth, so don't remove branches that have these small fruit. With fan-trained plants remove a quarter of all stems, back to a couple of inches of the main trunk, also removing all branches that are growing away from the wall or fence. April
Gooseberry Gooseberries fruit on spurs on two-year and older wood, remove crossing branches, trying to create a goblet shape. Followed by cutting off a third of the length of remaining stems. In mid-June remove any new shoots from the centre of the bush to reduce sawfly damage and allow plenty of air around the plant to reduce the chance of disease. Sawfly lay their eggs in the centre of the bush, when the caterpillars hatch they will start with the fresh growth before moving on to the rest of the plant. October
Grape vine Prune grape vines in December or January. Cut back last year's growth to one or two buds, removing the majority (80-90%) of the old growth,. This encourages new shoots which will bear the next season's fruit.
The old dead bark on the trunk should be gently scraped back to removing hiding places for any pests, such as mealybug and fungal spores.

Remove half of the bunches when they form in summer, to encourage the remaining fruit to swell and ripen.

Note: Pruning a vine at other times can lead to severe bleeding of the plant.

December
Passion flower Passion flower should be pruned in the spring. Spring
Pear See Apple and pear above Winter
Raspberry - autumn fruiting

Autumn fruiting raspberries fruit from the current season's growth. In October, cut all canes that have fruited, along with any that are damaged or diseased almost to ground level (4' / 10cm) then tie in any new fresh growth ready for next years fruit.

October
Raspberry - summer fruiting Summer fruiting raspberries bear fruit from one year old growth. In mid-autumn prune the old branches that have borne fruit this season, almost to ground level (4' / 10cm).

In mid-summer prune out younger shoots at ground level to leave 15cm (6in) space between them.

August
Red and white currant Red and white currants fruit on old wood, In March, cut back the main stems by a half and cut any new laterals to 1-2 in of last year's growth. Also thin out or remove any weak branches. March
Rhubarb Whilst not technically pruning, to stop rhubarb getting too congested. In October, lift the crowns every 4-5 years and divide. Split the crown into 3 or 4 pieces with a spade so each part has a 'eye' shoot and then replant the chunks a couple of feet (60cm) apart. October
White currant See Red and white currant. March