A Little History On Mulch
Mulches have been useful in landscapes and gardens since the dawn of man, and even before then! For as long as there has been plants and trees on earth that dropped their leaves or needles there has been mulch. The English word mulch is probably derived from the German word mulch, meaning soft, beginning to decay. It no doubt referred to earliest gardeners' use of straw, leaves, and compost spread on the ground to protect the roots of newly planted crops and other plants.
The Purpose of Mulch
There are many different types of mulch; from natural to man-made synthetics, but all perform the same basic functions in landscapes and gardens.
- help to conserve moisture in the soil
- good for suppressing weeds
- regulate soil temperatures, which can protect plants from extremes
- aesthetically pleasing and help to tie together plants and other elements in the landscape
- can help to control erosion
- last but not least, natural mulches decompose into rich organic matter that feeds the soil and helps plants thrive
Selecting the Right Mulch
Besides the mulch or compost you might make yourself, there are many types of mulch on the market these days. Understanding the attributes of different materials can help you choose the best mulch for a specific application. Below is a list of commonly used mulches and where I like using them.
Shredded Hardwood Mulches - These mulches are made from the pulp and/or bark of hardwood trees or other wood byproducts and are available in either natural form or various dyed colors such as red, brown, or black. They are shredded by machines into strips which makes them less susceptible to washing or erosion from rain or irrigation. Over time, shredded wood mulch will decompose into rich organic matter that feeds the soil. I like using shredded hardwood mulches in landscape beds or on gradual slopes that aren't to steep.
Pine Straw or Needles - Pine Straw is one of the least expensive landscape and garden mulches as it covers more ground per dollar spent than most other mulches. That being said, pine straw is the quickest of mulches to decompose. Pine straw helps to acidify soil so is a great choice of mulch for use in landscape and garden beds where azaleas, rhododendron, junipers, hollies, and other acid-loving plants are growing.
Pine Bark Mulches - Based on the size screen that was used during the processing to separate the various size pieces, pine bark mulches come in several different types and sizes. I like using pine bark "mini nuggets" or pine bark "mulch" in seasonal flowerbeds or other garden beds where small plants are spaced closely together and a smaller sized mulch is easier to fill between the plants. Pine bark large nuggets are most useful in larger, level or contained areas are are better for suppressing weeds.
Playground Certified Mulches - In most states there are regulations requiring certain types or forms of mulches to be used in any playground setting. There are also certain requirements for the depth or thickness of the mulch. Before installing playground mulch check with your local authorities to find out what types of mulch can be used in your area and at what thickness they should be installed. Certified playground mulches are designed to protect children by absorbing the shock from a fall. Most nursery and garden centers or mulch yards carry Playground Certified Mulches.
Stone or Brick - Many nursery and garden centers carry bulk or bagged river stones, marble chips, lava rock, brick chips and other types of stone products. The cost to cover an area with these products is usually considerably higher than with other mulches. However, stone is more permanent and often works out to be less expensive in the long run. I recommend the use of stone mulches in rock gardens, around garden ponds, around patios, for pathways, or in smaller landscape or garden beds. Stone has a tendency to heat up during the warmer summer months so be careful when using it around plants that might suffer from too much heat.
Wheat Straw - This and other types of straw are primarily used to suppress weeds and conserve soil moisture in vegetable garden beds or as a mulch over newly seeded lawns to prevent seed washing and to keep the soil bed damp, facilitating the germination process.
Rubber - Due to the toxic nature of most of the rubber mulches on the market, which are made from recycled tire materials, I do not recommend the use of these materials in the landscape or garden, or in areas where humans or wildlife will live, play or roam. Research indicates that rubber mulches made from tires emit toxic gases when heated by the sun.
And, last but not least: living groundcovers plants! - These plants aren't really considered a mulch however, when it comes to covering the ground, suppressing weeds, cooling the soil and tying other plantings together in the landscape, they serve the same purpose. There are hundreds if not thousands of varieties of low-growing, spreading or clumping groundcover plants available on the market today. There are groundcover plants suitable for use in almost any landscape or garden setting or environment. Some, such as spreading junipers, ivies, jasmine and euonymus are great for use as erosion controllers on steep slopes and embankments. Smaller creeping groundcover plants are useful to underplant shrubs or in to fill the spaces between stepping stones or pavers.
- In areas you plan to mulch, make sure they have been thoroughly weeded and watered.
- When using mulch permanently around plants and trees do not install any deeper than 2 inches. Doing so can either retain too much water or prevent rainwater and irrigation from reaching the roots of plants.
- As a temporary winter protection for tender plants mulch can be applied at most any thickness however should be removed or thinned when temperatures begin to warm in spring.
- During installation, use a garden or leaf rake to insure the mulch is spread evenly.
- If you plan to use a weed barrier product, avoid using sheet plastic as water, fertilizer and air cannot pass through. Instead, use always use a porous fabric that allows these elements to pass through.
- Do not use dyed wood mulches in playgrounds!
Mulch Spreading/Coverage Rates
Wood Mulch - approximately 200-220 square feet per cubic yard at 1-1/2" depth - or - approximately 7 square feet per cubic foot at 1-1/2" depth
Pine Straw - approximately 50-70 square feet per bale
Pea Gravel or Marble Chips - approximately 7 square feet per 50 pound bag
Lava Rock - approximately 7 square feet per 1 cubic feet
Wheat Straw - 200-300 square feet per bale