When to prune trees – experts reveal the best timings, and also the worst

Pruning trees is an important task that can help to enhance the beauty and shape of any ornamental tree. It also removes dead, diseased, or damaged branches that can all affect a tree’s future health. 

However, pruning can be a daunting job for many gardeners. If you have picked trees for privacy in a backyard, or inherited some lovely specimen trees, then you want to prune them correctly so you can enjoy them for years to come. 

If you find yourself wondering when is the best time to prune trees, then we are here to help. We hear from tree experts about getting the timing right to ensure you do nothing to risk the health of your trees.

When should you prune trees? 

It is imperative that all trees are pruned at the right time. It is not a one-size-fits-all approach when it comes to tree pruning and a failure to cut at the correct time is a tree mistake that has the potential to stress the tree and cause serious damage.

If you have very large trees that require attention, it might be advisable to consult professional tree experts regarding any pruning work. 

If you have trees in a small garden, or your trees are young or regularly trimmed to be at a more manageable size, then it is a task you can do yourself with clean and sharp garden tools.

When to prune deciduous trees

The majority of deciduous trees - ones that lose their leaves annually each fall - are pruned during their period of dormancy. Pruning them during dormancy is beneficial as they are placed under less stress from the act of pruning. 

As they are bare of leaves, it can also make it easier to see and assess the shape of the tree and make important decisions about what to remove, such as identifying dead, damaged, and diseased branches.

‘The best time to prune is when the plant is in full dormancy if it is a deciduous tree. A good rule of thumb is to not prune in months that end in R. (ie. October, November, December),' says Tamara Hogan, plant expert at Fast Growing Trees. ‘You will want to prune deciduous trees in late winter or early spring before we start to see the buds start to swell on the stems.’

Deciduous trees that are popular in many people’s backyard ideas include maple trees, crabapple trees, sorbus, and birch trees. 

However, birch trees are an exception to the winter pruning rule and are best pruned in late summer or early fall. They will flow sap if pruned in late winter or early spring and this can leave them susceptible to pests and insects. Another example of a deciduous tree to prune in summer is flowering cherry trees. 

Always do some research before trimming, to make sure you are not taking any risks and making a tree pruning mistake with the timing of your pruning.

Tamara Hogan

Tamara Hogan graduated from Utah State University with a degree in Ornamental Horticulture. She has worked within various horticulture fields since 2013. That includes floral design work, plant consults and teaching workshops at local nurseries, commercial greenhouse growing, and landscaping, before joining Fast Growing Trees.

When to prune evergreen trees

Evergreen trees do not lose their leaves in fall like deciduous trees. They go through changes during winter, but do not go completely dormant. Evergreen trees can also be pruned in late winter or early spring, before they start putting on new growth again. However, the exact time you trim may depend on your US hardiness zone.

‘In colder climates, it is best to wait until spring to prune evergreens,’ says Fern Berg, the founder of Tree Vitalize. ‘In areas that experience frost or snow, some of the more tender evergreens may be harmed by winter pruning.’

Fern adds: ‘If your evergreen flowers, wait until after it finishes flowering before pruning. If it doesn’t, you can prune as soon as the weather warms up in early spring to stimulate vigorous new growth.’

Some popular evergreens that are common in backyard landscaping ideas include cedar, eucalyptus, spruce, and cypress trees.

Fern Berg

Fern is the founder of Tree Vitalize and has planted and currently cares for over 100 different native and exotic fruit, nut, and ornamental trees.

Dangers of pruning at the wrong time

Making the pruning mistake of cutting at the wrong time comes with several risks to the tree. The right timing is important for the overall health, as well as the aspects of fruit and flowers. Indeed, if you prune flowering trees at the wrong time you can miss out on a year's worth of those gorgeous flowers. 

And trees can also be at more risk of disease, for example, pruning a flowering cherry tree in winter can leave them susceptible to silver leaf, a fungal disease more prevalent in winter that enters the tree through pruning cuts. 

Your climate will affect when you prune ornamental trees. Lisa Tadewaldt, founder at Urban Forest Pro, recommends some rules of thumb to help you make decisions about when to prune trees. 

‘If you live in a place that has extreme temperatures don’t prune during those seasons,’ says Lisa. ‘If you have hot summers or cold winters those are not good times.’ 

The type of tree needs to also come into consideration, as Lisa warns about ‘delicate ornamentals being more susceptible to damage from pruning in the wrong season versus a larger hardier tree’.

If deciduous trees are pruned too early, in late summer or early fall, then this can encourage them to put out a flush of weak growth as a result. The tree will put its energy into growing these new stems rather than preparing for dormancy. As a result, the young stems will be easily damaged by frosts and the overall hardiness of the tree can be impacted.

Lisa Tadewaldt

Lisa Tadewaldt is the founder and owner of Urban Forest Professionals, an arborist company out of Portland, OR, that has been serving that community for over 15 years

What is the worst time to prune trees?

The worst time to prune trees would be during periods of extreme weather. Whether this is high heat or extreme cold, both are capable of causing lots of harm to the tree. 

Fern Berg says that pruning during extreme temperatures will ‘place unnecessary stress on your tree, setting back its growth and possibly even resulting in die-back’. 

Lisa Tadewaldt goes even further and warns: ‘If you prune too far into winter or in the heat of summer the tree can react negatively and die back or die completely, but if you live in a milder climate this is usually not an issue except in the case of unexpected extreme weather.’

FAQs

When it comes to the likes of apple or pear trees, knowing when to prune fruit trees is important for healthy trees and bumper crops. Many fruit trees are pruned in winter, but not all. Stone fruits need to be trimmed in spring or summer and it would be a fruit tree pruning mistake to trim the likes of peaches or apricots during the winter.