Several large pine trees growing on either side of a dirt path, all leaning to the right
(Image credit: Cavan Images)

Many gardeners with big yards rely on their trees as the “bones” of the garden. Big trees also offer shade, block the wind, offer privacy, protection, and can feel like plant friends. That’s why it is worrying in more ways than one when a tree starts leaning.

Leaning, lopsided trees can be hazardous, but they aren’t always. Some are solid with strong root systems. There are a number of questions to ask when you see a tree leaning over before you consider cutting it down.

Why Is My Tree Leaning?

A tree that is leaning over can be a hazard. But that depends on several issues. One is when the issue started. If the tree grew in on a tilt and has been leaning ever since, it may be solid. But if it just started leaning after a big storm, it’s more likely to fall.

If you have a lot of trees, you may not be able to remember when the tree started leaning. In this case, look carefully at the trunk to see if you notice a growth pattern. Look at the side of the tree opposite the lean for uplifted soil.

Another idea is to consult photos of the area taken earlier to find out whether the tree was leaning. If it turns out that the lean is new, it may well result from root issues combined with high winds. Sadly, a mature tree that starts leaning after a strong storm rarely recovers.

Trees That Grow Sideways

Another factor to consider is the degree the tree is bent. As a general rule of thumb, the greater the angle at which the tree is leaning, the greater the risk for tree failure. Some say that a tree that leans more than 15 degrees from a stand-up position should be considered potentially dangerous.

But even a serious lean doesn’t necessarily present a hazard. The truly hazardous leaning trees are those that lean over a structure, a parking area, or an area that is frequently visited. A tree leaning over an empty field at the far end of the property may not be a high priority hazard. Another tree leaning at a less significant angle over a child’s play yard is the one to worry about.

Why Do Trees Lean?

Though winter storms can tip trees, there can be other reasons that your favorite tree is growing sideways. Trees often lean over when they are growing in a place that is largely in the shade. A tree can shoot up tall and thin in order to get their crown in the sun, but it can also angle over to one side if that is where sunlight comes in. This growing into the sun is termed phototropism.

This kind of lean can also appear like a curve starting part of the way up the trunk. These leans usually occur over years, giving the tree’s root system a chance to compensate by growing more and deeper roots on the far side of the lean for balance.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.