What Causes Moss to Grow on Trees?

Moss is prone to growing on trees under the following conditions:

• The tree is growing in a moist climate.
• The tree is planted in a damp area of the lawn.
• The tree’s trunk is well-shaded.
• There is good air quality.
• Your tree is sick or dying.

It’s important to assess the situation and determine why moss is growing. In most cases, the moss growing on your tree is perfectly harmless to your tree. However, there are rare instances where the host tree can be harmed by moss growth.

Is it Bad if Moss is Growing On a Tree?

It is very rare for moss to harm trees. Moss growing on tree bark doesn’t send roots into your tree or steal nutrients from it. For the most part, moss clings harmlessly to the bark and feeds on moisture and nutrients in the air. So, if you see moss growth on trees in your yard, it’s not a cause for alarm.

• Moss on tree branches and trunks is typically not harmful.
• Moss growth does not steal nutrients from a tree.
• If your tree is being overtaken by moss, it may be sick due to a tree disease.
• In some cases, an overgrowth of moss can cause damage to the tree.

While moss often grows on healthy trees, if your tree is losing foliage and experiencing a moss takeover, this may be due to a disease that is killing the tree. Although the moss is not to blame for the tree’s struggles, opportunistic moss will grow quickly on failing trees. In some rare cases, the moisture moss holds can cause bark rot or harbor bacteria and insects, but this is seldom the case.

What Does Moss on Trees Indicate?

If you see patches of moss growing on a vigorous tree, it often means the tree is a shady, moist area. In the Pacific Northwest United States, moss grows on the trunks of trees almost everywhere. This is due to the fact that moss loves the rainy, cloudy conditions in this region. If your tree has a big canopy that shades its trunk, it may be creating the perfect home for moss.

• The presence of moss indicates high moisture levels.
• Moss growth on a tree means that the trunk gets enough shade for moss to grow.
• Green moss growth shows that you have good air quality in your area.

Moss is also an indicator of good air quality. Mosses only grow where the air is clean and relatively free of pollutants. Smoggy air kills moss. So, a little bit of moss on tree trunks in your yard just means you live in a healthy area.

Does Moss Mean a Tree is Dying?

Moss growing on a tree does not necessarily mean the tree is dying. Plenty of healthy trees support moss growth without any harm to the tree. However, if the tree is losing foliage and moss is coating the tree branches, this could be a sign the tree is dying.

• Moss is not always a sign that a tree is dying.
• If your tree has healthy branches with plenty of leaves, moss growth does not indicate a sick tree.
• If your tree is losing foliage and the bare branches are quickly being overtaken by moss, this is a sign the tree is sick.
• Consult an arborist if you believe your tree may be diseased.

Tree moss tends to stick to the shaded portions of the trunk, but if a tree is diseased or dying, moss will quickly begin to grow on the moist, dead portions. If your tree has leafless branches where moss grows vigorously, it may be in need of attention from an arborist in order to save it. However, the moss is rarely the cause of the tree’s struggles. Often, it’s just a symptom.

How Do You Stop Moss From Growing on Trees?

If you want to stop moss growth or get rid of moss on trees, the best thing to do is treat the tree with a plant-safe moss-killing spray. Otherwise, you can kill the moss with a mixture of vinegar and water, or use a power washer to clean the moss off the bark.

• Use this moss killer spray to kill moss on trees.
• Trim the lower branches of your tree to allow sunlight to reach the trunk—moss won’t grow in sunny areas.

In order to keep moss from returning after you remove it, consider trimming the branches of your tree so that more sunlight reaches the trunk. Moss doesn’t grow well in sunny areas, so by allowing direct sunlight to reach mossy areas, you can kill off the moss and prevent it from returning.

What Does Moss On a Tree Mean?

Moss on a tree indicates that there are high levels of moisture and shade on or near the tree, as well as high-quality air. Moss loves to grow in moist, shaded areas where a tree’s branches cast natural shade on the trunk. It also won’t grow in regions with polluted air. In most cases, moss won’t harm your tree. The two plants can peacefully coexist. However, if the moss seems to be overtaking a tree, or the tree starts losing leaves out of season, the moss growth may be a sign that the tree is sick.