News Release
December  3, 2007

Landscaping Tips: Rocks add interest to Wyoming landscapes

By Tom Heald, UW extension educator, and Mary Sabel, Master Gardener emeritus

Rocks are an enormous part of the landscape we call Wyoming, and using them in a home landscape ties a property to its surroundings, reinforcing a Western sense of place.  

Rocks have a variety of uses such as pathways and borders, mulches and even main features. 

Flat rocks are best used for pathways. No two rocks are the same so a pathway can become a kaleidoscope of sizes and shapes. Leaving room between rocks gives a gardener an added benefit of being able to plant ground covers for a more natural look.

With water conservation on many people’s minds, rock mulch is great to consider, particularly in a xeric (low water) flowerbed or where Wyoming winds would make shambles of wood chip mulch. 

Consider either pea gravel, crushed limestone or weathered granite. Two inches of rock mulch applied to the surface of the soil is recommended. Besides saving up to 50 percent on water bills, mulch will also help smother weeds. 

Be careful where rock mulch is placed. We’ve seen it applied zealously into and over the crowns of plants, killing them as effectively as if they were weeds. When placing mulch around plants, make certain no part is buried.

The question arises whether landscape fabric should be used under mulch.

Landscape fabric (not solid plastic) allows water and air to easily pass through its porous fabric and does an excellent job in preventing weed seeds to germinate. But in high wind areas where soil is transported by the wind, we find there is enough soil deposited on top of the fabric in a few short years for weeds to grow. This reduces its effectiveness to prevent weeds.

It is highly recommended NOT to use solid plastic as a base under mulch as it allows neither water nor air to get to the soil, and it can actually lead to poor plant health.

Really BIG rocks or small boulders can have a dramatic and beautiful impact to a landscape, but don’t just place these big rocks on the surface of the soil. A boulder can look out of place and appear fake. 

To make big rocks “look right,” bury them up to a third or more to make them appear like they’re part of the natural landscape, and add mid-sized and smaller rocks along one side as if they were caught there during erosion or stream flow.  

Once in place, these big rocks will create micro-climates. The north side will provide cool shade for plants adapted to this environment. This protected area will also help the plants from breaking dormancy at the wrong time in early spring. Sun- and heat-loving plants will do well on the south side of the rocks.

Many Wyoming communities have nurseries, landscape supply companies, concrete operations and other businesses that sell gravel, rocks and boulders for the home landscape.  Those knowledgeable with landscaping can assist in determining the right rock for your project, and many are equipped to deliver and even place it.

Tom Heald is an area educator for the University of Wyoming’s Cooperative Extension Service (UW CES) in Converse, Natrona and Niobrara counties. He is based in Casper and can be reached at (307) 235-9400 or theald@natronacounty-wy.gov. Mary Sabel of Casper is a landscape consultant and UW CES Master Gardener emeritus.

Contact: Robert Waggener, Editor
Phone: (307) 766-3571
E-mail: robertw@uwyo.edu

###