The Tree on the Property Line: Who Owns It in Ontario, and How Far Can You Trim Your Neighbour’s Branches?

Plant it, prune it, take it down: Ontario’s Forestry Act and Toronto’s tree by-law each say something different about all three, and on overhanging branches the written law goes quiet.

I’m Arthur Zhao, a Toronto real estate broker. Picture something mundane: two neighbours agree to replace the rotting fence between their yards, the crew pulls the old boards, and there it is — a maple that the fence had been quietly routed around for decades, its trunk sitting right on the line. Nobody had thought of it as anyone’s tree in particular. Now the fence builder wants to know whether he can trim the low limbs to fit the new panels, one neighbour is wondering whether this is the moment to finally take the tree out, and the other is thinking about planting a hedge along the new fence instead.

Those are the three things anyone can do to a tree on a boundary: plant one, cut part of it, or take it down. Ontario law treats each one differently, and in Toronto there is a second layer of rules on top of the provincial one. Below I go through each action in turn — what Ontario’s Forestry Act says, what Toronto’s tree by-law adds, and where both of them simply stop talking.

What makes a tree a “boundary tree”

Two definitions apply in Toronto, and they are worded a little differently.

The provincial one is in section 10(2) of the Forestry Act: “Every tree whose trunk is growing on the boundary between adjoining lands is the common property of the owners of the adjoining lands.” Note what the test turns on — the trunk. Branches and roots crossing the line do not make a tree common property under this wording.

Toronto’s private tree by-law, Municipal Code Chapter 813, defines a boundary tree as one “any part of whose trunk is growing across one or more property lines” (§813-11, added in 2015). The City’s own permit guidance puts it plainly: a boundary tree “is owned by both (or all) property owners.” The by-law also has a separate category, the neighbour tree — a tree growing wholly on one property that the owner next door applies to injure or destroy.

Action one: planting on the line

What the Forestry Act says. Section 10(1) is the only place the Act talks about planting on a boundary: “An owner of land may, with the consent of the owner of adjoining land, plant trees on the boundary between the two lands.” Consent comes first, and it is the neighbour’s consent, not the City’s.

What Toronto’s Chapter 813 says. The private tree article is built around injuring, destroying and removing trees (§813-12); it does not set up a permit for planting one on your own land. Planting does show up as an obligation, though: when the City grants a permit to destroy a tree, replacement trees have to be planted and kept in good condition for two years (§813-20A), and the article’s protections then apply to those replacement trees even though they are under the usual 30-centimetre threshold (§813-20H).

What neither one says. The Act does not spell out a specific consequence for planting on the boundary without consent. It also does not say what happens to a tree planted wholly on one side that, decades later, has a trunk wide enough to cross the line. If you are planting close to a fence, that is a question worth putting to a lawyer before the tree goes in, not after it has grown.

Action two: trimming and pruning

What the Forestry Act says. Nothing about pruning or trimming as such. Section 10(3) makes it an offence to injure or destroy a tree growing on the boundary without the consent of the land owners. The Act does not define “injure,” so it does not tell you which cuts cross that line and which do not.

What Toronto’s Chapter 813 says. Here the by-law is more specific. It defines injury as “any act that will harm a tree’s health in any manner” (§813-11). It requires a permit to injure, destroy or remove any tree with a stem diameter of 30 cm or more, measured 1.4 metres above ground (§813-12). And it carves out an exception: no permit is needed for “pruning of a tree in accordance with good arboricultural practice to maintain tree health” (§813-13B). The City’s guidance adds that a permit “does not authorize an applicant to encroach or enter upon another person’s private property.”

What neither one says. How far you may cut back branches from a neighbour’s tree that hang over your yard. Neither the Forestry Act nor Chapter 813 draws that line. Whatever rule governs it comes from outside these two texts, and I have not verified it for this article — so I am not going to state one. If the branches belong to a boundary tree, keep section 10(3) in mind: a cut that injures the tree without your co-owner’s consent is the thing the Act prohibits. For your specific situation, ask a lawyer before the saw comes out.

Action three: removing the tree

What the Forestry Act says. Destroying a boundary tree without the consent of the land owners is an offence under section 10(3). The penalty is in section 19(1): on conviction, a fine of not more than $20,000, imprisonment for not more than three months, or both. Being one of the owners does not get you around this — the consent required is that of “the land owners,” plural.

What Toronto’s Chapter 813 says. According to the City of Toronto’s permit guidance, “either (or any) property owner may apply for a permit if required however, consent must be granted by the other property owners(s).” When an application to injure or destroy a boundary tree comes in, the City must notify every co-owner in writing and tell the applicant that the arborist report and other supporting documents will be shared with them (§813-19.1). The by-law’s penalty section sets a minimum fine of $500 and a maximum of $100,000 per tree, plus a special fine of $100,000 under the City of Toronto Act, 2006 (§813-29). I covered the permit application itself in a separate article on removing your own tree, so I won’t repeat the steps here.

What neither one says. What happens when the co-owner simply says no. Neither text provides a tie-breaker, a deadline for answering, or a way to compel consent. That gap is where a dispute stops being a by-law question and becomes a legal one.

Three actions, two layers of rules

What I’d still take to a lawyer

The two texts leave several practical questions open. These are the ones I would not try to answer from the statute alone:

• How far branches or roots from a neighbour’s tree may be cut back from your side.
• What remedies exist if a co-owner refuses consent, or if a boundary tree was damaged or removed without yours.
• Whether a tree that started on one side has become a boundary tree as it grew.
• Who pays for work on a shared tree. Neither text I have quoted addresses cost-sharing.

This article covers the Forestry Act and Toronto’s Chapter 813 only. Other Ontario municipalities have their own tree by-laws, which I have not reviewed here — check with your city before relying on any Toronto figure above. Even within Toronto, trees in ravine-protected areas fall under a separate chapter of the Municipal Code (Chapter 658), which this article also does not cover.