A mulched planting bed has a great appearance and trees that are mulched are less prone to damage caused by lawn equipment. Besides creating a safe haven around trees, mulch can also provide many benefits including developing a healthy root system.
There are many types of mulch to choose from including inorganic mulches and organic mulches. Lava rock and stones are an example of inorganic mulch. Inorganic mulches do not break down which means you will not have to replenish often. However, inorganic mulches do not provide any ‘extras’ to the tree as organic mulches do. Bark, woodchips, and compost mixes are examples of organic mulches. Organic mulches have many benefits such as helping to maintain soil moisture, controlling weeds, improving fertility of the soil and providing insulation to the tree. Insulation around the tree helps to keep soil cooler in the summer time and warmer in the winter.
Mulching properly is a must. Even though there are many benefits of mulching, too much can be harmful. Mulch ‘volcanoes’ as we know them, are a no no. Putting mulch directly against the trunk of a tree can stress stem tissue and can lead to insect and disease problems. Mulching too deeply can also lead to an excess of moisture in the root zone which can cause stress and root rot.
The general recommended mulching depth is 2 to 4 inches. Community Canopy recommends a minimum radius of 18”or 36” diameter circle around the tree. If you are able to provide mulch to the tree’s drip line (see illustration) or beyond, I’m sure your tree would thank you.