Submitted Photo Wood mulch is better to use around a tree than rock mulch. Photo by Ken Eraas.

We all want our trees to grow fast and provide us with shade and add beauty to our yards. With our short growing season and dry weather such as we are having now, trees need all the help we can give them to prosper.

There are a couple of lawn tasks that we do regularly which are very harmful to them.

The first of these commonly done yard practices is lawn mowing. When grass is left around the tree trunk, many times the mower deck will run or hit the lower trunk of the tree. This can tear bark and deeply score the trunk.

The second practice is use of a weed whip or string trimmer. Again, with grass growing very close to the trunk, the trimmer is used to cut this grass. In doing this, many times the trunk is also hit with the string. When repeated many times, it will remove the bark and cut into the tree.

These injuries will slow the growth of the tree and the open wounds will be a place where disease and decay organisms can attack the tree. In some instances it will kill the tree. If not killed, these wounds will weaken the trunk of the tree. This will make it more prone to breaking off and falling from high winds or snow loads as the tree grows.

By keeping grass from growing close to the trunk of the tree, we can avoid the need to get either the mower or trimmer close to the trunk. And, by keeping the grass away from the tree, it will also grow faster!! Research has shown that trees without grass growing around them will grow four times faster than trees with grass growing up to the trunk. This is especially true with young trees and transplanted trees. Grass can be killed with a herbicide or by shallow tillage around the tree.

After the grass is removed, another thing you can do to keep the mower and trimmer away, and help the tree grow is to mulch with a wood mulch around the trunk. To a point, the larger the mulched, grass free area, the faster your tree will grow. No landscape fabric is needed under wood mulch. Make the mulch 3 to 4 inches deep with it slightly shallower right around the trunk. Since perennial flowers are not very competitive for moisture and nutrients, the can be planted in the mulch to add beauty and color around the tree.

Rock mulch is not as desirable around trees as it gets extremely hot in sunlight which can damage the shallow roots of the tree and stunt its growth. Rock mulch against the trunk can also score and damage the bark.

Ken Eraas is the Ward County Extension Horticulture Assistant. You can reach him by calling 857-6444 or emailing kendell.eraas@ndsu.edu.