Trees: Too Much Mulch

Mulch volcanoes are commonly found here in West Tennessee.  They are huge mounds of mulch piled against the trunk of a tree or shrub.  This is detrimental to the health of the tree.  It can lead to excessive moisture around the trunk which is a breeding ground for canker diseases and rot.  Beware, it also can become a home to rodents!

Sometimes this thick layer of mulch can become too dry.  Moisture has a hard time penetrating because a fungus layer forms.  Water is then shed away from the tree.  In a wet season, the opposite can take place.  Beds with a thick layer of mulch do not dry out!  This is important on clay soils or in newer subdivisions where soil is compacted and drainage is poor.  Roots need oxygen.  If the soil is always saturated with moisture, roots began to decline.

Volcanoes should be pulled away from the trunk down to the trunk flare.  Then mulch the tree properly with 2-4 inches of mulch.  Keep mulch a few inches away from the trunk.  More mulch is not better.  Mulching properly is one of the best cultural practices.  Here are a few reasons why you should mulch properly:

• Prevents erosion
• Retards weed growth
• Holds soil moisture
• Decomposes and enriches soil
• Is aesthetically pleasing
• Protects plant from mechanical injury
• Promotes unity among a group of plants
• Reduces heaving of soil in winter
• Helps maintain uniform soil temperature

To sum it all up, 2-4 inches of mulch over the roots of a new tree or shrub is one of the best practices, not 20 inches!  Eradicate volcanoes near you before it’s too late!