Proper mulching techniques important

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Tree Talk, Joanna Angle

While driving along a busy street in a nearby city, I noticed ornamental trees in the median standing in what are called mulch volcanoes.

Shredded mulch had been piled in circles almost a foot deep at the edges and nearly two feet high against the trunks.

It never ceases to amaze me that people (in this case, taxpayers) actually spend money to have this kind of  landscaping done because it is a major no-no for tree care.

Coincidentally, that same day we received one of the quarterly mailings from our arborist, Billy Manning, and it happened to be about proper mulching techniques.

Much of what follows is taken from a brochure produced by the International Society of Arboriculture (ISA).

First, mulching can be one of the easiest and most beneficial things property owners can do for the health of their trees. Mulching helps retain moisture in the soil, controls the growth and spreading of weeds and insulates soil from temperature extremes. Mulch can improve the soil’s fertility, aeration and drainage, as well as protect against certain plant diseases. Mulched trees are less likely to be hit by weed eaters or lawn mowers.

However, too much mulch (more than 2 to 4 inches) does more harm than good.

On wet, moist soils, deep mulch will hold moisture on roots causing them to rot.

Piling mulch against trunks can stress tissues and create habitat for insects and gnawing rodents. Mulch buildup from reapplications to refresh color can create matted blankets that hinder the penetration of air and water.

When purchasing mulch, remember that organic mulches which include tree bark, pine straw, wood chips, leaves and other products that come from plants are preferable to inorganic mulches made from pulverized rubber, rock, stone and some geotextiles.

Unlike organic mulch materials, inorganic mulches do not decompose to add nutrients to the soil and improve its structure.
Last, when possible place mulch over the entire root system area.

Ideally that is from near the trunk to the drip line (edge of the canopy) and beyond.

For more information on mulching and other topics related to trees, visit the ISA consumer information website www.treesaregood.com.

– Joanna Angle is a Master Tree Farmer and 2012 South Carolina Tree Farmer of the Year. Her Cedarleaf Farm in Chester County is a Certified Stewardship Forest and part of the American Tree
Farm System.