Xeriscape gardening in Las Vegas part six

Commercially available soil amendments and mulches  photo by Judy Holly

Preserving soil moisture is another important aspect of xeriscape gardening.

Any means that can be employed to reduce the amount of evapotranspiration from the soil surface means that more water is available to garden and landscape plants. Catching what little rainfall there is and keeping it from running off is also an integral part of preserving soil moisture.

One of the most widely used methods of conserving soil moisture is a layer of mulch.  Mulches are very good at reducing evaporation and run off during heavy rains. For desert soils there are many products now that can be incorporated into the soil that will absorb water when it is in excess and hold it until the plants need it.  This is particularly important when establishing new plantings. Using the proper spacing of plants in the landscape allows for the full utilization of available soil water resources by each plant. Many kinds of mulch materials are available at nursery and home supply stores that can be purchased ready to spread for different garden styles. Even layers of gravel and rocks are a type of mulch that aid in the prevention of soil erosion from wind and slow down the movement of water or rainfall on a slope. Forest floors are naturally covered with mulch from all the leaf and other plant and animal litter. The desert creates a gravel cover on the soil after the wind blows away all the loose sand and silt.

Organic mulches made up of different materials, sizes and colors are produced and sold in garden supply stores neatly packaged in bags for easy hauling to garden sites. Organic mulches that contain pine bark also have fungicidal properties and cedar mulches may repel some insects. There are advantages and disadvantages to all kinds of organic mulches so it is best to do a little research or test a small area before applying a large amount of mulch to a large area. Some of them float during rain or excess watering and could run off into swimming pools, sidewalks and other non-garden areas. There are some kinds of insects that thrive in mulch materials and act as decomposers of organic materials. This may be a concern to those who don’t like any kind of bugs around the home.Underneath organic or stone mulches, some form of weed mat or plastic is usually laid down first on the bare ground. This landscape cloth layer acts as a barrier to reduce weeds and prevent the mixing of the mulch with the soil. Typically the weed mat is laid down and pinned to keep it from blowing around. The edges need to be turned under and pinned properly or covered with a good layer of soil to prevent fraying. If an edge starts to come loose it is best to pull it back a little and then pin down again and recover it before the wind can whip up the whole edge.

When larger plants will be planted in a gravel or mulched area the weed mat or soil fabric is laid first and then holes are cut where each plant will be planted. The plants are planted through the holes and then the mulch materials are laid down on top of the weed mat for neat clean and even finished look and to hold the landscape fabric in place.