“How to Mulch and How Not to Mulch”
Correct mulching around the base of your tree can be very beneficial to the
health and appearance of your tree; however improper mulching can severely
damage and open your tree to invasion for insects and disease.
Trees growing in natural mainly untouched
settings such as forest preserves have their feeder roots which are located
in the top 6 to 12 inches of the soil are anchored in well-aerated soil full
of essential nutrients. The forest floor is covered with organic matter such
as leaves and fallen twigs. These decaying natural materials replenish
nutrients and provide an optimal environment for root growth and mineral
Landscapes in residential areas
and yards have poorer soils, little organic matter, competition with grasses
for moisture and extreme changes in soil temperature. Applying a 2 to 4 inch
layer of mulch around the base of a tree can provide a more natural
environment and improve tree health care.
When to Mulch
Mulch can be applied any time of year when trees or shrubs are planted. The
best time to apply mulch around established trees or bed areas is mid-spring
when soil temperatures have warmed up enough for sufficient root growth.
Mulch should be applied 2-4 inches in depth
over relatively clean, weed-free soils. No more than 2 inches if soil is not
well drained; up to 4 inches if drainage is good. More finely textured
mulches should be no thicker than 1 to 2 inches. Never pile mulch more than
4 inches high. Do Not allow mulch to touch tree trunks; keep mulch 3-5
inches away from trunks of young trees and 8-12 inches from trunks of older
Types of Mulch
There are mainly two types of mulch organic and inorganic. Inorganic mulches
include various types of stone, lava rock, rubber chippings and other
materials. Inorganic mulches do not decompose and do not need to be
replenished often. However inorganic mulches do not improve soil structure,
add organic materials, or provide nutrients. Organic mulches include wood
chips, pine needles, hardwood and softwood barks, cocoa shells, leaves,
compost mixes, and a variety of other products usually derived from plants.
Although most organic mulches decompose faster and must be replenished often
the decomposition process improves soil quality and fertility.
Benefits of Proper Mulching
- Helps maintain soil moisture.
- Reduces the germination and growth of
- Serves as nature’s insulating blanket.
Mulch will keep soils warmer in winter and cooler in summer.
- Mulches will improve soil aeration
- A layer of mulch can inhibit certain
- Can improve soils fertility
- Mulch can give planting beds a uniform,
well cared look.
Problems Associated with Improper
- Mulch exceeding 4 inches around the
root zone, can stress the tree causing root rot.
- Piling mulch against the trunk or
stems of a tree can stress stem tissue, and may lead to insect or
- Thick layers of fine mulch can
become matted, and may prevent the penetration of water and air to
the root zone.
- Deep mulch provides hiding places
for rodents that can chew extensively on the bark around the trunk.