XERISCAPE: LANDSCAPING WITH STYLE in the ARIZONA DESERT

       


Top Dressing
Inorganic mulches, also known as "top dressing," are commonly used in Xeriscapes to cover the soil and are considered part of a yard's hardscape component. Top dressing not only reduces water evaporation and weed growth, it also gives your planted areas a finished look.

Decomposed granite and crushed rock are the types of top dressing most commonly used in our area. Both are available in a variety of sizes and colors. Before selecting a top dressing, decide on the overall effect you want to achieve. Do you want your mulch to match the color of your house or would you like it to provide a bit of contrast? Do you like a very natural look or a more stylized look? Do you want your yard to blend with a common neighborhood landscape scheme or would you like something a little different from the neighborhood norm? Then consider your maintenance style. Some types of decomposed granite and crushed rock are easier to rake than others. Some kinds minimize the appearance of plant litter. Finally, consider your long-term landscape plans. Top dressing is neither inexpensive nor easy to replace. Do some research and shop around before you buy.

A colorful, low-maintenance Xeriscape.
Photo credit: Kent Newland

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Top Dressing Tips
  • As a general rule, your layer of top dressing should be 2-3 inches thick. This will help to inhibit evaporation and weed growth and provide consistent coverage with less chance of developing bare spots in the future.
  • Measure the total area of your yard to be covered with top dressing. Call or visit suppliers who can help you determine the amount of top dressing needed to cover the area. Typically, one ton of granite or rock covers about 120 square feet.
  • It is NOT advisable to put a layer of black plastic beneath your top dressing. Over time, the edges will dry out and curl up and may become unsightly. In addition, black plastic prevents air and water from reaching plant roots.

Four Things You May Not Know About Mulches
  • Mulches cover and cool the soil. During the summer, cooler soil temperatures help to improve root growth.
  • Water evaporates more slowly from soil surfaces that are covered and cool. Mulches help to reduce water use by reducing evaporation so more water stays in the soil for plants to use. They also help to reduce salt buildup in the soil.
  • Mulches help water to penetrate the soil more effectively, reducing runoff from planted areas. Reduced runoff keeps water where plants can use it.
  • Mulches help to keep sunlight from reaching weed seedlings in the soil. Less sunlight means less weed growth. Weeds use water that would otherwise be available for landscape plants. Fewer weeds means more water for your plants and less maintenance time for you.

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A colorful, low-maintenance Xeriscape. The stabilized pathway made of very fine decomposed granite bisects planting areas covered with larger-sized granite mulch. Boulders lend a nice touch. The brick-colored decomposed granite matches the colored concrete sidewalk and entry steps and contrasts with rim of water feature. Natural-looking planting mounds include well-placed boulders and top dressing of decomposed granite. Summer color in this urban Xeriscape - Texas Ebony (tree), Red Bird of Paradise (shrub/right), Lantana (groundcover), Petite Oleander (shrub/left) Mulches help reduce evaporation from soils, minimize weed problems and provide a finished look for landscapes.

 
 
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