How to prune birch trees – arborists reveal 5 golden rules to follow and 3 things you should never do

Pruning birch trees is essential to keeping them healthy and looking at their finest. The importance of understanding how to prune a birch tree properly cannot be overstated, especially as bad trimming can have catastrophic effects.

Scott Seargeant, a consulting arborist and owner of Seargeant Landscape & Arboriculture, warns how dangerous improper pruning is for birch trees. He claims: ‘A large percentage of their untimely death has to do with mis-pruning. Birch trees get borer insects and several diseases, all of which can be exacerbated by mis-pruning and over-pruning.’

Given that stark warning, here are five expert-recommended rules to keep trees healthy and three tree pruning mistakes that can jeopardize the health of a birch tree and must be avoided.

How to prune birch trees - 5 rules to follow

1. Prune at the right time - Picking when to prune a birch tree is key. If done correctly, the tree will recover perfectly from the pruning and live a long and happy life. However, if done incorrectly, the tree can be stressed and highly vulnerable to infections and pests, most notably the bronze birch borer. The time to prune is late winter, around a month before the buds swell, or in the late summer - never prune birch trees in spring.
2. Use clean and sharp tools - Any tree pruning must be done with clean and sharp pruning tools. The typical garden tools for trimming birch trees will include pruning shears, loppers, a pole pruner, and a pruning saw. Make sure that any tools are sharp, it not only makes pruning easier but means clean cuts easier for the tree to heal. And make sure the tools are clean, as sterilized tools avoid transferring diseases around the garden.
3. Start with the 3D’s - The starting point with pruning birch trees is identifying dead, diseased, and damaged branches and completely removing them. Removing these 3D’s preserves the tree’s health and helps with light penetration and air circulation into the canopy. Next, remove any crossing branches that may rub and create entry points for diseases, as well as branches growing upward other than the leading stems.
4. Prune for safety - Scott Seargeant recommends looking for branches ‘in the way of pedestrians, cars or blocking line of sight’ and removing them for safety reasons. These should ideally be removed when they are young to reduce the impact of pruning. Scott advises only pruning ‘small diameter branches’ so pruning cuts are quick and easy to heal. ‘I do not like pruning any living, structurally sound branch more than one inch in diameter,’ he says, advocating focusing on removing dead branches and just small, alive wayward branches as required.
5. Consider every cut - Mason Hanrahan, a certified arborist and president at Tim-O-Tree, claims ‘the most important element of the pruning process is branch selection’. He advocates for asking why you are potentially cutting any branches to make sensible decisions, this includes prioritizing cuts for structural integrity over ‘cutting a branch because you don’t like how it looks’. Scott Seargeant claims that ‘usually, there is no strong reason to prune anything else’ after removing dead, diseased, damaged, and crossing branches and any blocking lines of sight. ‘However, if there is a strong compelling reason(s) then prune them last,’ he adds.

Scott Seargeant

Scott Seargeant is an award-winning international consulting arborist and owns a full-service landscape installation company. His expertise lies in diagnosing tree conditions, providing treatment, and recommendations, selecting appropriate trees for planting, and offering guidance on post-planting tree care

How to prune birch trees - 3 mistakes to avoid

1. Heavy pruning - It is a pruning mistake to be aggressive when pruning birch trees. A key part of understanding how to prune birch trees is to be conservative and measured with every cut. The US Forest Service warns of some potential dangers of over-pruning birch trees. It says: ‘Excessive pruning (greater than 25% of the live canopy) should always be avoided. Heavy pruning increases light penetration to the root zone and can increase soil temperatures and reduce soil moisture levels.’ Removing more than 25% will weaken the tree and even be fatal. It means you always want to be selective when pruning.
2. Topping the tree - Scott Seargeant warns to ‘never top’ birch trees. Tree topping is cutting the top of a tree if you feel it is getting too large. However, it can affect the look and health of a birch tree. ‘Topping birch trees destroys their natural character, vigor, and causes them to produce epicormic shoots from their trunks and basal areas,’ claims Scott. Topping trees also create large wounds in the main trunk that are vulnerable to pests and diseases. It will also cause dieback that leaves birch trees more prone to storm damage.
3. Making improper pruning cuts - Whatever reason you prune tree branches, removing them properly and safely is paramount. Mason Hanrahan warns: ‘When cutting birch trees, it is important to ensure you are not leaving tearing or stubs.’ Remove larger branches in sections to avoid bark tearing or splitting and creating a large, open wound at risk of infection. To prune tree branches, make a small cut on the underside a few inches away from where the branch meets the trunk. Then cut from the top a few more inches up the branch to break it off, before removing the remainder at the branch collar.

Mason Hanrahan

Mason Hanrahan is an ISA-Certified Arborist (ON2491-A) and Qualified Tree Risk Assessor. He practices arboriculture in Ottawa, Canada, focusing primarily on tree removal and tree risk mitigation. Mason has been running Tim-O-Tree since 2018 and loves sharing knowledge and educating the public about trees.

Shop tree pruning tools

FAQs

How do you reduce the height of a birch tree?

Rather than topping the tree to control the size, it is best practice to do crown reduction, also known as drop-crotch cutting, to reduce the height while keeping the shape and beauty of a birch tree. It is recommended to get professionals to reduce the height safely to ensure the continued health of the tree.

Birches can be great trees for privacy and allow you to enjoy the bark as part of a beautiful screen. However, how you use birch trees will depend on the size and design of a space. There is a huge variety of birch trees of different sizes and characteristics, so always pick a type that fits your particular space. Thankfully, the options include dwarf birch trees suitable even for small backyard ideas.