Pruning a tree or shrub involves removing specific branches to benefit the tree as a whole. It is important to know the best time to prune before you start, which is one of the reasons it is often wise to employ a tree surgeon. Different kinds of trees and shrubs require different care, and there is no one single rule of thumb for when to prune.
Pruning at the right time of year keeps your plants healthy, beautiful and productive. The proper pruning times of common garden trees and shrubs are outlined below.
First off, why are you pruning this particular plant?
If a branch is diseased, dead or damaged, tree surgery should generally be conducted immediately. If you are planning to prune for aesthetic reasons, to reduce the size of an overgrown plant, or to revitalise an aging tree or shrub, you should generally wait until early spring or late winter. Most (but by no means all) trees and shrubs are dormant at this time, but just about ready to awaken for spring. This means that any tree surgery will cause the least amount of disruption to the plant, and the wound will heal when the tree comes out of dormancy. The damage will also have the longest possible time to heal before the following winter, which reduces the chance of damage to the tree substantially.
From a practical standpoint, pruning a dormant tree or shrub is also much easier, as the leaves are not in the way, and the branches are at their most visible. There will also be the least amount of yard waste to dispose of at this time. Ideally, you’ll prune just before the plant’s buds begin to open. Some trees, especially dogwood or maple, will bleed sap if pruned in the early spring, but this is not generally a cause for concern.
If waiting until late winter or early spring is not possible, pruning can be done at any time of the year with minimal danger to the plant, but it is best to avoid doing so in cold winter weather, or hot dry weather if possible. If you will be pruning a tree or shrub after its leaves have opened, remember that it has just expended a great deal of energy. Try to wait a bit to let them build up their reserves again before you prune, and consult a tree surgeon if you are uncertain how to proceed.
As noted in detail below, some trees and shrubs do not follow this pattern, and are better pruned at other times. For example, some woody plants form buds at the end of their growing season, and those buds only bloom the following spring.
Here are some examples of when different types of trees should be pruned
Narrow-leaved evergreens, including most conifers like yew, pine and juniper, are best pruned late in the winter or early in the spring. This is the best time to prune if your intention is to shape the tree, cause it to grow in a more ‘bushy’ fashion, or to remove any superfluous branches.
Broad-leaved evergreens such as privet, escallonia, euonymus, box and Japanese holly, which are grown more for their foliage rather than for their flowers, are best pruned late in the winter or early in the spring.
Most Deciduous Trees also respond well to winter/spring pruning, ideally in February, March and the first part of April. Any later and most will have started to produce leaves already. Deciduous trees are also more prone to bark slipping or tearing after their foliage comes in. Pruning deciduous trees should be avoided while they are losing their leaves during the fall as well, as they are more vulnerable while they prepare for winter dormancy.
Again, expect some trees like dogwood and maple to bleed sap when pruned in the spring. This will not harm the tree, and is a part of the healing process, like a scab works to heal human skin.
Oak Trees should not be pruned during April and May, as this timing can increase the tree’s vulnerability to oak wilt. April and May are when sap beetles are most active in many places, and they can spread the oak wilt fungus from infected trees to the pruned sections as the feed from the sap. Oaks are better pruned during February or March if at all possible.
Fruit Trees are generally best pruned between the latter half of February and the first part of April. If pruned in the fall or the early winter, many fruit trees are more vulnerable to winter injuries than non-fruiting trees. If pruning at this time is necessary, a skilled tree surgeon should be able to minimise any damage.
Deciduous Shrubs should be handled in different ways depending on their types. These types of plants are commonly planted because of their flowers, so pruning should take care to preserve the flowers if possible.
Many types of deciduous shrub do not produce particularly attractive flowers. They are more commonly cultivated because their berries, leaves, or bark are considered attractive. Like deciduous trees, these shrubs are best pruned between February and April.
If at all possible, avoid pruning deciduous shrubs in the latter part of the summer. This could cause a late flush of new growth, which will not be well developed when the weather turns and might be more vulnerable to winter injury and disease.
Spring flowering shrubs bloom from buds grown the previous season. Both forsythia and lilac fall into this category. The best time to prune these types of shrubs depends on their overall condition, and how much you intend to prune from them.
Old, large and overgrown shrubs can often benefit from very extensive pruning. This practice can renew and rejuvenate such plants and greatly improve their appearance. Large overgrown shrubs should be pruned back between late February and early April, before they begin to grow new leaves. This will mean few if any flowers will form this year and possibly next year as well, but it is generally worth the price to restore health and vigour to the plant. Again, if you are unsure how to proceed, your local tree surgeon can help.
Spring blooming shrubs that only require light pruning should be seen to as soon as possible after blooming is complete. Not only will you get to enjoy the flowers this year, but the shrub will be in the best position to flower again next spring.
Summer-flowering shrubs like Japanese spirea or potentilla generate all their buds in the spring. Therefore they are best pruned in February, March and April, and will still be able to bloom in the summer as usual.