Benefits of Mulching Your Lawn Clippings
Mulching brings big benefits to gardening
Mulching certainly is not a new gardening practice. I frequently extol the virtue of organic mulches in maintaining soil moisture, suppressing weeds and improving the soil.
The technical definition of a mulch is any material that provides protection or improves the soil.
In addition to helping decrease surface evaporation and weed control, mulches also can improve water penetration, moderate soil temperature fluctuations, protect shallow-rooted plants from cold temperature injury, guard against frost-heaving from successive freezing and thawing, and improve soil structure and nutrient availability.
There are two basic types of mulch - organic and inorganic.
Organic mulches are plant derived and include wood chips, bark chips, straw, grass clippings, sawdust, seed hulls, pine needles and even crushed corncobs and grape crushings.
Inorganic mulches are inert and include both man-made materials - such as plastic film, polyester fabric, and fiberglass - and natural materials, such as crushed lava-rock and gravel.
What is the ideal mulch for your yard or garden?
Characteristics to look for in a landscape mulch are:
-- It's attractive and uniform in color and particle size.
-- It's not a fire hazard.
-- It doesn't blow away easily.
-- It breaks down relatively slowly.
-- It allows good movement of air and water, and it doesn't compact readily.
-- It's weed free.
In the vegetable garden, most of us probably don't have to be as particular about the appearance of the mulch,
but in return, we want a temporary mulch that provides some measure of weed control and helps improve the soil with added organic matter.
We also want a mulch that doesn't rob nitrogen from the soil when it's turned under and starts to decay.
High carbon or "brown" materials, like sawdust and straw, will lead to nitrogen tie-up in the soil.
For effective weed control, most mulches should be applied at a depth of 3 to 4 inches. Looser, more open materials,
such as straw or pine needles, should be applied at a depth of 6 inches. One cubic yard of most mulching materials
will provide a 3-inch layer over a 100-square-foot area.
Materials that have a tendency to compact or mat, should be applied in thinner layers. Keep all mulches at least
six inches away from the base of woody plants. This prevents injury to the tree trunk from freezing and thawing.
It also avoids problems with excessive moisture right at the tree base and will deter rodents, which might reside in the
mulch, from eating the bark.
Let's talk about the good and bad points of some of the most commonly used mulches in area
landscapes and gardens.
Bark: In my opinion, bark is the best mulch for landscapes. It's attractive, it allows good movement of water and air,
and it helps add organic matter to the soil as it breaks down.
While bark gradually does decay and loses its nice earthy brown color, it easily can be renewed with a top
layer of bark every couple of years.
Bark also moderates soil temperatures and keeps the roots of young landscape plants cooler during hot
I'm partial to medium-sized, shredded bark, but others prefer the bark chips or chunks.
I believe the shredded bark is less likely to blow away,
and it looks more natural to me. Bark also tends to be somewhat expensive, but I think it's worth it.
Black plastic: For years, black plastic was touted as our weed-control savior, but alas, it had some
undesirable features, which has led to its drop in popularity.
First of all, black plastic tends to deteriorate with time because of exposure to heat and ultraviolet radiation.
Once it starts to break apart, it no longer controls weeds effectively, and it often becomes an eyesore.
If the plastic is covered with mulch, it's difficult to remove the plastic.
Plastic also does not provide for good air and water movement into the soil. In many landscapes,
it has been detrimental to the development of healthy root systems.
Weed-barrier fabrics: Woven polyethylene and spun-bonded polyester fabrics have replaced black plastic
on the garden store shelf. These generally are easy to apply, and they do reduce weeds. Most are treated to
withstand ultraviolet radiation and generally last longer than black plastic in the garden, especially when
covered with a mulch.
Unlike plain black plastic, most allow good movement of water and air into the soil.
Their drawback is they tend to be fairly expensive and eventually they do deteriorate.
I like to use weed barrier fabrics in the vegetable garden.
Three years ago, I bought one of the fabrics, and it disintegrated in less than a month.
Last year, I bought a different brand and was much happier. It's held up well, and I was able to use it again this year,
even after its exposure to full sun for a year.
I find the fabrics very useful for controlling weeds in with my vine crops, like tomatoes and squash. It also keeps
the fruit from direct contact with the soil.
Grass clippings: For those still collecting them instead of recycling them by leaving them on the lawn, grass clippings
are an inexpensive mulch that can be very useful in vegetable and flower gardens.
Breaking down rapidly, grass clippings also add organic matter and nitrogen to the soil. Grass clippings should be
allowed to dry before using them as a mulch. It's also important not to apply grass clippings too thickly,
because they tend to compact and mat badly.
If the grass clippings come from a weedy lawn, you may be introducing weeds into your garden with the clippings.
Lava rock, stone, gravel: I find rock mulches an abomination - in most cases. Used alone, they don't provide
effective weed control, especially for weedy grasses. They don't moderate soil temperatures.
In fact, they can lead to very high soil temperatures and damage the roots of landscape plants,
especially younger plants and shallow rooted species.
They also can raise temperatures around plants and create a higher water demand on them.
As you can guess, I find rock mulches aesthetically displeasing - they just don't look natural.
To me, their only positive points are they are not a fire hazard and they don't blow away in the wind.
Rock mulches probably should be used in areas where wildfire is a persistent threat.
Pine needles: For some reason, gardeners think pine needles should be avoided.
For those with access to pine needles as a mulch, go ahead and use them.
They're attractive, and they don't compact.
They are an excellent winter mulch for strawberries and tender perennials.
They could acidify the soil over time, but since we have quite alkaline soils to begin with,
this isn't a problem. One drawback -pine needles are quite flammable and can be a fire hazard.
Grape crushings, processed hops, crushed corncobs:
Using these or similar materials is an environmentally sound idea, but gardeners should watch for problems.
They may compact when fresh and wet, preventing adequate water and air flow to the roots.
They may have an undesirable odor, especially when fresh, and molds might form on the surface.
The colors of these products vary, and their appearance may not be attractive, depending on individual tastes.
These "plant by-products" can be used with careful management and attention to potential problems.
However, it's important not to overdo it with excessively thick layers.