There are a few short-term fixes if tree roots emerge in your lawn. But the best plan might just be to remove the lawn and create a new garden space.

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In the Garden

Q: Tree roots have come up to the surface in our lawn. It’s so bad the lawnmower blade hits them. What is causing this, and what is the best way to deal with them without harming the tree?

A: There are several reasons tree roots come up to the surface. Although some kinds of trees, such as poplars and ornamental cherries, are prone to produce surface roots, usually they’re a sign of poor soil conditions. Heavy clay or compacted soils lack the air and moisture necessary for proper root growth below ground, so roots are forced to come up to the surface to find what they need for survival.

Unfortunately, as the tree grows, surface roots also increase in size, and if they are on a lawn they can become so large they can make mowing difficult, if not impossible.

Covering surface roots with soil won’t solve the problem. Adding too much soil at one time can suffocate tree roots, while adding a bit at a time is pointless because the soil simply dissipates and disappears into the lawn.

If necessary, surface roots can be removed, but it must be done properly or it could harm the tree. During the dormant season, remove only one large root or two smaller ones per year. Allow at least 10 inches of distance from the trunk for every inch of the diameter at ground level before making the cut.

To prevent the likelihood of disease problems, first dig a trench around and under the root; then use a clean, sharp lopper, or in the case of very large roots, a pruning saw to make a clean cut. Finally, do not apply pruning paint. If all goes well, new roots will form and grow from the cut end.

Of course, the best longterm solution is to remove the lawn where the surface roots are causing a problem and turn the area into a garden bed. You’ll have a wonderful new garden space to enjoy and you won’t be forced to spend hours of backbreaking work every dormant season removing roots and/or replacing broken mower blades.

Q: Twenty years ago, I built a treehouse for my children. It is still there, suspended by 1-inch rope between four fir trees that are clustered together. I am going to take it down but the rope has become buried deep in the bark of the growing trees. Do I pull it out or leave it and just let the tree envelop it?

A: This situation illustrates why we shouldn’t wrap anything tightly around the trunk or branches of a tree. As the tree grows and increases in girth, if wire or rope is left in place encircling a branch, over time it will cut into the tree, causing a condition known as girdling.

Girdling can harm a tree in two ways. First, it blocks nutrients from moving past the constriction, preventing carbohydrates from reaching the roots. If the girdling occurs on a main trunk, it can lead to stunted root growth and endanger the stability of the tree. If girdling is severe, you will notice a large bulge made up of blocked nutrients above the restriction.

The second problem is that if the tree grows around and envelops the encircling material, it can create a weak spot where the tree could break in a windstorm or a heavy snow.

If the rope can be removed without seriously harming the bark, the damage is minimal and you probably don’t have to worry about it. If the rope is enveloped and can’t be easily removed from a trunk or major limb, and the tree is located where falling branches could cause harm, call in a certified arborist to assess your tree.