October pruning of trees, shrubs and climbers
October sees the start of the dormant season which is the best time to prune lots of deciduous garden trees. You can prune newly planted trees to remove any damaged growth and help balance the shape of the canopy as well as maintain a dominant main leader. Damaged and lop-sided growth can be removed from many established specimens too, but consult a professional tree surgeon before tackling anything substantial and make sure the tree does not have a preservation order on it before you start. It’s also not too late to complete the pruning jobs for September if you haven’t got round to them yet. Here. I’ve given practical advice for pruning santolina, birch, hornbeam, honey locust, walnut, laburnum, tulip tree, crab apple, parrotia, plane tree, ornamental pear, oak, willow, mountain ash and Japanese snowball.
SHRUBS
Santolina (after flowering)
Remove the faded flower-heads along with any straggly shoots in autumn. As the shrub ages it may become open exposing ugly woody growth. In this situation, cut back the flowered shoots to within 2.5cm (1in) of the old growth during early spring.
TREES
Betula (birch)
Birch trees need little regular pruning, but when they are young it is a good idea to cut off lower branches to allow a clear length of trunk. Pruned during the summer they can bleed profusely, but if pruned when fully dormant the sap flow will have slowed down.
Carpinus (hornbeam)
Another tree that’s prone to bleeding if pruned in spring or summer, so it is best tackled now. Most hormbeam trees will form an attractive, well-balanced canopy without intervention and so require no pruning other than the removal of crossing or wind-damaged branches. Young trees should also be encouraged to produce a clear trunk, so remove lower side branches to gradually raise the canopy as the tree grows. They can be trained as standards, dense hedges or pleached to look like a hedge on legs.
Gleditsia (honey locust)
Honey locusts should be trained as a single-leader standard. Little routine pruning is required other than the removal of crossing or damaged branches. Lateral branches that form low down on the stem should be removed as the tree matures to leave a clear trunk up to 2m high to provide sufficient room for the naturally downward-curving branches.
Juglans (walnut)
If you haven’t pruned your English or black walnut yet, there’s still time before the onset of winter. These trees are both prone to winter damage when they are young, so if the main leader is damaged, cut it back into healthy wood and train up another leader to take its place. Do not prune older trees unless absolutely necessary. They are prone to cavities after severe pruning if the collar at the base of the branch is damaged or stumps are left behind. For this reason it is worth raising the canopy when the tree is still young and keeping the stem clear as it grows.
Laburnum (golden rain)
Laburnums are best pruned anytime from the end of the summer, up until Christmas. Pruning earlier in the year should be avoided because they are prone to bleeding. Laburnums make excellent specimen trees or can be trained as an eye-catching standard or over a sturdy arch or pergola to help show off their spectacular flower trails. Specimen trees should only be pruned to improve the shape of the canopy and to remove damaged stems, while trained forms will need regular pruning to maintain the shape of the plant so that the flower trusses can be clearly seen. Take care to remove any shoots that appear from below the graft union on grafted trees. Laburnums are prone to cavities after severe pruning if the collar at the base of the branch is damaged or stumps are left behind. For this reason it is worth raising the canopy when the tree is still young and keeping the stem clear as it grows.
Liriodendron (tulip tree)
Prune tulip trees while dormant, which means anytime from the end of this month until February. They naturally form a single-leader standard, so little routine pruning is required other than the removal of crossing or damaged branches. Lateral branches that form low down on the stem should be removed as the tree matures to leave a clear trunk up to 2m high.
Malus (crab apple)
Another tree to tackle during the dormant season. Different species of crab apple naturally produce different-shaped canopies and so pruning requirements vary slightly. Some flowering crab apples, such as Malus floribunda, tend to produce a shrub-like, multi-stemmed bush when young, maturing to form a lollipop-shaped canopy of well-spaced branches on a single stem. Prune initially to create a single main stem, and then only to improve the balance and overall shape of the canopy. Remove badly placed or damaged branches, as well as lowest branches to produce a clear stem. Crab apples that naturally produce a dome-shaped canopy of evenly spaced feathered branches, such as the popular ‘Golden Hornet’ and ‘John Downie’, also can be enhanced as they mature by removing the lowest branches to raise the canopy. A few crab apples, such as Malus hupehensis, produce a flame-shaped canopy with a single main leader. These require no pruning as a rule, unless the leader is broken and several lower branches compete to replace it. If this does happen, select the best positioned and cut back the others by about 15cm to an outward-facing bud. When pruning all crab apples, fast-growing vertical shoots, known as ‘water shoots’ may be produced as a response, and these should be removed completely as soon as they are noticed. Mature crab apple specimens should not be pruned other than the removal or damaged branches, since they are prone to fungal infections.
Parrotia (Persian ironwood)
No routine pruning is required. Parrotias can be trained in two ways: shrub-like specimens may need overcrowded shoots thinned to avoid congested growth; while tree-like, standard specimens with a clear stem may need lower branches shortened to reveal the ornamental bark. Prune any time during the dormant season.
Platanus (plane tree)
This popular street tree can be trained as a standard with a single leader and a clear trunk to 3m or as a feathered tree with branches down to near ground level. In either case, little pruning is required other than the removal of crossing or damaged branches. Poorly shaped crowns can be balanced during the dormant season by cutting out misplaced shoots and branches. As the tree matures, remove the lower branches to create a clear stem. Even on feathered trees, aim to remove branches below 1.2m so that the naturally drooping lowest branches that remain do not touch the ground. Established trees tolerate heavy pruning so that the crowns can be reduced or thinned to keep within bounds or to allow more light to filter down to ground level in summer. However, these are major operations and should only be carried out by a trained professional tree surgeon.
Pyrus (ornamental pear)
All ornamental pears, including the popular variety ‘Chanticleer’, should be trained as a single-leader standard with a pyramid-shaped canopy. No routine pruning is necessary except to remove badly positioned or damaged branches that unbalance the overall shape. Aim for evenly spaced side branches all the way around the trunk. Also remove lower branches over several years as the tree matures to create a clear trunk up to 2m. Even the weeping silver-leafed pear, Pyrus salicifolia ‘Pendula’ needs a clear stem to allow sufficient room for the cascading branches.
Quercus (oak)
Train young deciduous oaks as a single-leader standard so that they form the classical dome-shaped canopy as they mature. Evergreen oaks, such as Quercus ilex, should be allowed to form a more feathered structure to the canopy so that the leader is only slightly more dominant than the surrounding side shoots. Hedges of Quercus ilex should not be trimmed until April and again in early September. With all oaks, no routine pruning is required other than the removal of crossing or damaged branches. Lateral branches that form low down on the stem should be removed as the tree matures to leave a clear trunk up to 2.5m. More serious renovation of mature specimens should only be carried out by a trained professional tree surgeon.
Salix (willow)
Willows grown as trees should be trained as a single-leader standard. Little pruning is required other than the removal of crossing or damaged branches any time during the dormant season. Weeping willow are best left alone unless you want to raise the canopy of mature specimens to create a clear 2m trunk to achieve a more classical weeping silhouette. Willows grown as shrubs for their ornamental stems need annual pruning. Top-grafted weeping forms of willow, such as the popular ‘Kilmarnock’, also should be pruned annually once well established to maintain their overall shape. Thin out branches to create a tracery of evenly spaced stems that form a complete skirt around the tree. Then shorten the branches that remain to an outward-facing bud so that new growth will reach the ground by the end of the coming growing season. Also remove any upright or horizontal growths that spoil the cascading shape of the canopy.
Sorbus (mountain ash, rowan)
All sorbus should be trained as single-leader standards. Little pruning is required other than the removal of crossing or damaged branches which can be carried out any time during the dormant season. Lateral branches that form low down on the stem should be removed as the tree matures to leave a clear trunk up to 2m high. On grafted specimens, suckers that are produced below the graft union should be removed completely as soon as they are noticed.
Styrax (Japanese snowball)
This shrubby tree should be trained as a single-leader initially, allowing a feathered crown of branches on a short trunk, so that the leader is only slightly more dominant than the surrounding side shoots. No routine pruning is necessary. However, lower branches will be shaded out as the tree matures and such branches can be removed completely.
CLIMBERS
Parthenocissus (Boston ivy, Virginia creeper)
Boston ivy and Virginia creeper will need new shoots tying into their supports for the first couple of growing season after planting. Once established, prune anytime from now until Christmas to keep the plant within bounds, paying particular attention to stems that are encroaching on windows, guttering or roofs. Old and neglected plants respond well to severe pruning and can be cut back to plump buds about 1m from the ground at this time of year.
