If you are planting a tree near a fence, you may hope for a formula you can use to determine the ideal distance between them. Like animal species, however, tree species vary in so many ways that the only simple answer is: It depends. Some trees are small and delicate, while others are forces of nature that whisper to the angels. Some have roots that rip out sidewalks, and some drop leaves or smelly fruit or hundreds of flowers to the ground beneath it. To determine spacing for tree planting, you need to take many elements into account.
Size counts when it comes to tree spacing. Some mighty coastal redwoods (Sequoia sempervirens; U.S. Department of Agriculture hardiness zones 7 to 9) stand 379 feet tall, while a mature 'Tamukeyama' Japanese maple (Acer palmatum var. dissectum 'Tamukeyama'; USDA zones 5 to 8) tips in at 8 feet tall. Obviously, the taller and broader a tree, the farther it should stand from a fence.
Your Tree's Function
Think about what you expect your new tree to do in the future, or what you expect to be doing with it. If you are planting a fruit tree, you probably have expectations of harvesting fruit at some point and will want access to all sides of the tree. Take tree function into account when determining tree/fence spacing.
Root of the Problem
Some tree roots lift sidewalks and raise sewer lines that get in their way, but many don't. A tree with a single deep tap root rarely causes any soil-surface issues, but those with aggressive, shallow roots should not be allowed within spitting distance of a brick wall. Fences are not destroyed as easily as a wall, and the severity of the risk depends on the amount of the fence that touches the ground. Cutting back aggressive roots is not a good option, since root disturbance damages and can even endanger a tree.
When trees drop leaves, fruit or flowers, the detritus generally lands on the ground beneath the tree. For example, deciduous trees drop their leaves every year, and unharvested or inedible fruit ends up on the ground as well, as do flowers and pine cones. If you plant a tree so close to a fence that its canopy extends over it, the falling plant parts may land on the other side. This can be a problem for boundary fences, and your neighborhood association or city might have laws in place to prevent it. Plan your planting to make sure the entire canopy of the mature tree is on your side of the fence.
Utility Lines Get Top Priority
It's better if trees and power lines do not mix it up, since the tree is not likely to come out on top. If power lines are strung up above your fence, plant your tree sufficiently far away that its crown will never interfere with the utility lines. Similarly, you don't want to dig into an underground line when you are shoveling a hole for planting. Ask the utility company about underground lines in the area before you begin.
Make Way for Rights of Way
Check before you begin digging to see whether anyone owns an easement or a right of way over the area of your property where you are installing the tree. An easement is a legal right to use some part of real property that doesn't belong to you. A right of way simply means the right to use a piece of land as a passageway to somewhere else. If you find either on the property where you intend to plant the tree, consult a legal professional before you go further.