Mulch -- not just for looks
Send a link to a friend
CHAMPAIGN -- Many homeowners
choose to mulch because they enjoy the well-cared-for look it gives
their landscape. But, they may not realize they are also providing
many benefits for their trees. With mulch, the result can be a
better growing environment for trees and their roots.
Homeowners should be aware that, generally, the root system of a
tree spreads out, not down. "The roots of most trees extend out a
significant distance from the trunk. Most of the fine, absorbing
roots of trees are located within inches of the soil surface," says
Jim Skiera, executive director of the International Society of
Arboriculture. These shallow roots are essential for taking up water
and minerals for trees, and they require oxygen to survive. A thin
layer of mulch, spread widely, can provide a healthier environment
where these roots grow.
Properly applied mulch provides many benefits to the health of a
tree. Unlike trees growing in a forested environment, urban trees
are not typically planted in an optimal environment for root growth
and mineral uptake. Typically, urban environments are harsher, with
poor soil conditions and large fluctuations in moisture and
temperature. Applying mulch can help reduce the stress of such
conditions through these benefits:
Helping to maintain
soil moisture with less evaporation.
Reducing the number
by keeping soil cooler in the summer and warmer in the winter.
damage caused by lawn equipment such as Weed Eaters and lawn
fertility, aeration and drainage.
Organic or inorganic
Mulches are either organic or inorganic material mixtures that
are placed over the soil surface around the base of a tree. Mixtures
consisting of various types of stone, rock, pulverized rubber and
other materials are labeled as inorganic. Because these types of
mixtures do not decompose, they need replenishing less often.
However, this also means they do not improve soil structure, provide
nutrients or add organic materials to the soil. Inorganic mulches do
still provide other benefits, such as insulation and protection.
Organic mulches consist of wood chips, pine needles, bark, leaves
and other products derived from plants. These mulches decompose;
thus, they are very beneficial in improving soil quality by
replenishing nutrients. They do, however, require more maintenance
because decomposition creates the need to replenish more often.
[to top of second
Mulching dos and don'ts
In order for mulch to be beneficial, it must be applied
correctly. "'All things in moderation' should be a homeowner's
mulching motto," says Skiera. "As beneficial as mulch is, too much
can be harmful in more ways than one." Too much mulch can create
excess moisture that may lead to root rot. Other problems created by
over-mulching include insect and disease problems, weed growth,
sour-smelling planting beds, and chewing rodents.
To ensure the health of your trees and plants, follow these
practical mulching tips to landscape like the pros:
Apply a 2- to 4-inch layer of mulch unless a drainage
problem exists; then a thinner layer is recommended. Do not add
mulch if there is already a sufficient layer; instead, rake the
old mulch to break up any matted layers and refresh the
mulching. Avoid placing mulch against the tree trunks. If
mulch is already piled against the stems or tree trunks, pull it
back several inches so that the base of the trunk and the root
crown are exposed.
Mulch out to the tree's drip line or beyond if possible.
The International Society of Arboriculture, headquartered in
Champaign, is a nonprofit organization supporting tree care research
and education around the world. As part of the society's dedication
to the care and preservation of shade and ornamental trees, it
offers the only internationally recognized certification program in
the industry. For more information and to find a local ISA-certified
[International Society of
Arboriculture news release]