by Francis Kilkelly
Mulching is the practice of placing a loose surface onto the
surface of soil in your flower or vegetable garden in order to
protect, insulate and beautify the area. This loose covering is
called a mulch and it can be either of an organic or inorganic
variety. Examples of mulches include compost, stone and grass
clippings. Every gardener should understand the many benefits of
mulching the soil in their garden. This article will discuss the
benefits of mulching, how to choose the correct mulch and have a
quick look at some of the different types of organic and
inorganic mulches available.
Benefits of Mulching
Let us explore some benefits of mulching:
- Prevents soil erosion - Soil erosion happens when winds or
water slowly wear away the surface of soil and remove it.
Mulching your soil will prevent this as there is now a
protective, replaceable layer.that comes between the surface of
the soil and the forces of nature above it.
- Insulates the soil in winter - The harsh temperatures of
winter can be unkind. Mulching the soil in winter will insulate
the soil preventing it from repeated patterns of freezing and
thawing and will insulate plant roots. It prevents heaving
(buckling upward) of soil in spring. Mulch should be applied to
the soil when it has frozen and removed in spring only when
there is no danger of further frosts. Winter-mulched soil thaws
out more quickly in the spring.
- Cools down soil in summer - A layer of mulch in summer
protects the soil beneath from the extreme heats of summer and
reduces the need for constant watering i.e. water retention is
- Helps against soil compaction - The layer of mulch acts as a
buffer or extra layer between entities that can cause compaction
on the soil below e.g. people, equipment, heavy rains.
- Improves appearance - A mulch applied to your bed can make it
look more complete and attractive. This varies from mulch to
mulch as some are more attractive and natural looking than
- Prevents weed growth - One of the more useful benefits of
mulching is in weed prevention. While the mulch itself will not
stop weeds from germinating it serves to act as a barrier
between the weeds and the outside world above. When a weed
reaches the mulch layer it will not be able to break above it
and it will eventually die back. Some mulches perform this weed
prevention feature better than others. Depth of mulch is also a
contributing factor. Care should be taken however when selecting
mulches as some mulches like grass clippings and straw may
actually contain weed seeds.
- Keeps fruit and vegetables clean - A layer of mulch reduces
the chances of fruit and vegetables getting dirty from splashes
from the soil below.
Choosing the Correct Mulch for Your Garden
Careful thought should be given when choosing a mulch to apply
to your garden as each is different and should fit in with your
exact requirements. Here are some common factors that should be
- Soil pH suitability - Some mulches like bark mulch and pine
needle mulch can affect the pH value of soil so they are best
used on soils containing acid-loving plants.
- Removal in spring - Certain mulches need to be removed in
spring because they can smother emerging plants. Examples
include stone mulch and bark chips.
- Cost - Is cost a limiting factor in your choice of mulches? If
so you can find your mulch for free if you choose certain types.
If you keep a compost heap then you will have compost for
mulching. Other free mulches (if you have the sources) are pine
needles and grass clippings.
- Appearance - Do you care about how the bed will look when the
mulch is applied? Each mulch adds a different look and depending
on the design of your garden you may want to choose a mulch that
matches it in colour and texture.
- Penetration by water and air - Some mulches are better at
allowing water and air to pass through them than others. This
may be important depending on a plant's watering requirements.
- Addition of nutrients to the soil - Organic mulches add
nutrients back into the soil when they decompose. The nutrient
types and their amounts added back into the soil depend on the
mulch and it varies quite a bit. Using compost as a mulch
guarantees plenty of nutrients for your plants.
Some Types of Organic Mulch
This type of mulch once used to be living material and as such
will decompose over time. During their decomposition vital
nutrients will be added back into your soil. However you may
want to avoid using organic mulches if you have rodent problems.
Some common organic mulches are:
- Compost - Mulches and feeds the soils as it decomposes. This
mulch is free if you have access to your own compost heap. Apply
at a depth of 1 - 3 inches.
- Pine Needles - Commonly used with acid soils. Cheap, looks
great and allows water to pass through freely to the soil below.
It decomposes quite slowly however. Apply to a depth of 1 - 1.5
- Straw - Provides great insulation, water penetration and weed
control. Care should be taken that straw does not contain weed
seeds itself. Apply to a depth of 6 - 8 inches.
- Grass Clippings - Readily available and decomposes quite
quickly adding nitrogen back into the soil. Try not to apply too
fresh as it can heat up quite a bit and possibly cause damage to
your plants. Apply to a depth of 1 inch.
- Newspaper - Provides great weed control and is readily
available. Apply another mulch on top to keep it in place. Apply
in 2 layer sections.
Some Types of Inorganic Mulch
Inorganic mulches are inert materials that have not originated
from living material. Sometimes inorganic and organic mulches
are used in conjunction with one another. For example a
geotextile (inorganic mulch) may be covered and held in place by
bark chips (organic mulch). Some common inorganic mulches are:
- Stone - Looks great and provides great insulation. If removal
in spring is a factor in your choice of mulch avoid using stone.
Degrades very, very slowly. Apply to a depth of 2 - 4 inches.
- Plastic - Does not decompose so it does not add anything into
the soil. Acts as a great weed control and is easily laid. Must
be perforated to allow water to pass through. Apply in a
thickness of 1 - 6 mm.
- Geotextile - Expensive blanket-like synthetic fiber that
provides great weed control and allows for water penetration.
Almost always used in conjunction with a cover mulch (e.g. bark
chips). Apply in a single layer.
In this article we looked at the many benefits of mulching and
the different types available. Maybe take the time today to
decide which mulch to use in your garden if you have not mulched
in the past. You may be surprised at how cheap the process can
be if you use mulches such as compost from your compost heap,
grass clippings from your lawn cuttings and/or the Sunday
newspapers! Happy mulching.