Hello,

By late November the garden is well and truly dormant, so it’s a good time to prune many deciduous garden trees. As for October, 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 October if you haven’t got round to them yet.

Here, I’ve given practical advice for pruning acer, alnus, amelanchier, ash, bean tree, beech, black gum, flowering dogwoods, davidia, eucalyptus, horse chestnut, hawthorn, hornbeam, horse chestnut, katsura tree, mulberry and sweet gum.

SHRUBS

Amelanchier (snowy mespilus)

This large multi-stemmed shrub or tree initially can be pruned to open the centre of the crown. Damaged, misplaced and diseased stems should be removed, with the remained thinned out if necessary. As specimens mature they may need renovating by cutting out one-in-three stems, starting with the oldest. After a three-year period, the whole shrub will have been rejuvenated. Amelanchier lamarckii can also be trained as a single stemmed tree. No routine pruning is necessary. However, the lowest branches can be removed as the tree matures to leave a short clear trunk.

TREES

Acer (maple)

The dormant season is the time to prune acers because they tend to bleed heavily at other times. Any time between November and February is ideal. Specimen trees such as A. davidii, A. negundo, A saccharinum, A. campestre, A. griseum and A. platanoides should develop a central leader with a well- balanced head of branches. Remove badly positioned, crossing or rubbing shoots and branches and cut out any twiggy growth from the clear trunk under the canopy to show off the bark to best effect. Acers grown as multi-stemmed trees on a short trunk, such as A. palmatum, should require very little pruning other than to remove frost-damaged and weak shoots, as well as any badly positioned, crossing or rubbing stems.

Aesculus (horse chestnut)

All horse chestnuts 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 2-3m high to provide sufficient room for the naturally downward-curving branches. All pruning should be carried out after leaf fall.

Alnus (alder)

Most alders naturally form multi-stemmed trees, but also can be trained as single-leader standards. Prune and train in autumn by selecting a suitable leader and then removing lower branches gradually as the tree develops up to a height of about 2m. Thereafter, little routine pruning is required other than the removal of crossing or damaged branches. All pruning should be carried out after leaf fall.

Castanea (chestnut)

Train young chestnuts as single-leader standards so that they form the classical domed-shaped canopy as they mature. Thereafter, 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 3m. More serious renovation of mature specimens should only be carried out by a trained professional tree surgeon.

Catalpa (bean tree)

The bean tree 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. Catalpa also responds well to very severe pruning and can look effective as a pollarded specimen – simply cut back all new growth to a bud 3-8cm from an established framework of stubby branches every other year.

Cercidiphyllum (katsura tree)

The katsura tree requires minimal pruning other than the removal of any broken, diseased or crossing branches during late autumn or winter. It naturally forms either a single-leader standard or a multi-stemmed tree. In the latter case, branches that form low down on the stem should be removed as the tree matures to leave a clear trunk up to 1-2m high. Avoid hard pruning.

Cornus kousa, Cornus controversa

These dogwoods should be trained as a 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 for C. controversa and up to 1m for C. kousa. Avoid hard pruning.

Crataegus (hawthorn, May)

The ideal time to prune hawthorn is once the fruit has been eaten by resident birds and other garden wildlife, but before early spring. Most forms require minimal pruning, other than the removal of broken, diseased or crossing branches. Encourage them to form a single-leader standard tree by removing lower branches as the tree matures until there is a clear trunk about 2m high. Alternatively, cut back a recently planted hawthorn to encourage it to produce a multi-stemmed tree ideal for use in a naturalistic planting or wild area of the garden. Trim hedges in summer.

Davidia (handkerchief tree)

Requires minimal pruning but does have a tendency to produce competing leaders so will need pruning to maintain a strong leader in the first few years. Remove any broken, diseased or crossing branches in late autumn or winter. 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.

Eucalyptus (gum tree)

Eucalyptus gunnii grown for its ornamental juvenile foliage will need pruning now. Cut back all new growth annually on both coppiced and pollarded specimens. Specimen trees that require pruning to maintain the balance of the canopy can also be tackled now. They also respond well to heavy pruning, so if a tree becomes top-heavy it can be cut back, lopped or topped before growth starts in spring.

Fagus (beech)

Leave new trees unpruned except to remove broken stems or to balance the canopy. Once very well established (say, six years after planting), remove the lower side branches when it is dormant – spreading the pruning over a period of several years. If there are competing leaders, this can spoil the overall shape and balance of the tree as it grows, so remove the weakest. Larger trees can benefit from having the lowest branches removed so that the naturally drooping branches are clear of the ground. In time, raise the canopy to about 2m. Purple beech can produce reverted green shoots from time to time and these should be removed completely. Weeping beech should have any uncharacteristic growth removed and once the branches reach the ground they can be cut back to a healthy bud. Take care not to cut all branches to the same length so that the appearance remains natural. Hedges are best pruned in mid-winter or mid-summer.

Fraxinus (ash)

Most ash 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. Do this now before new growth starts. 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. Weeping standards of F. excelsior ‘Pendula’ should only be pruned to remove crossing stems or thinning out congested branches. Take care not to over thin and open up the canopy too much, aiming for evenly spaced branches right around the crown where it joins the main stem.

Liquidambar(sweet gum)

Although regular pruning is unnecessary, it is worth checking that young specimens have formed a single, central leader. If there are competing leaders, this can spoil the overall shape and balance of the tree as it grows. Larger trees can benefit from having the lowest branches removed so that the naturally drooping branches are clear of the ground.

Morus (mulberry)

Mulberries are best pruned between November and the end of the year because they are prone to bleeding if pruned in spring. White mulberries 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 eventually leaving a 1.5m clear trunk. Alternatively, you can create a character tree that looks prematurely aged by pruning out the leader once well established and allowing the tree to spread naturally.

Nyssa (black gum)

Young specimens may need pruning to maintain a balanced canopy and to promote branching. Aim for a feathered framework of up to half-a-dozen branches. As the tree matures, remove the lowest branches to form a clear trunk up to about 1m so that the naturally drooping lowest branches that remain do not reach the ground. Also, the appearance of older specimens can be spoilt by vigorous upright shoots produced within the canopy. These should be removed completely while the tree is dormant.