Functional walls can be a major design element in the garden.Credit: Photo by Jane Gates
Retaining walls are simply structures that retain something – usually soil – safely away from where you don't want it. They are often used to hold back or define the edges of hills and slopes. They can also be constructed as decorative elements or to create or divide up space.
Landscape retaining walls can be made with a number of materials, but they need to be constructed durably to weather the elements and handle physical pressures. Stone and cast cement in the form of blocks are excellent choices. Design, however, is limited only by the imagination of the designer.
Plan the look of your wall to harmonize with other structures in your landscape. For example, if you have a rustic styled house you may want to echo the look by using rough-hewn stone and follow through with rough-cut wood fencing and furniture. Or a Southwestern themed garden may be enhanced by designing stucco-coated surfaces or by using Arizona flagstone.
You can build your own creation with any of the interlocking cast concrete blocks being sold for the purpose. There are assorted colors, textures and styles of block available to match any landscape look. If you want to construct a strong, stable retaining wall – the kind that would be necessary to hold back the weight of soil – make sure you build it properly. Cement block set into place with concrete should be reinforced with rebar. Remember to add gravel and pipe for drainage behind the wall as an outlet for the water that will build up in the soil being retained by your structure.
Another decorative way to build a barrier or blocade is by using dry stacked stone. But be aware that the building of traditional stacked stone walls is an art and there are experts who specialize in them. Rocks have to be carefully fitted and stacking is done with the exact right angles to make them stable.
In many parts of the United States retaining walls three feet or higher need building permits. Check with your local city hall to find out what building codes are in your area.
These are just some tips on landscaping retaining walls. Additionally, you can build these structures to offer double duty as a seating benches, table tops or counters. Or use them to surround a raised vegetable bed, partition off a patio space or set off a fire pit area. You can even add pots to the top edge for decoration or build in planters that will allow a low wall to grow tall with a living fence of narrow shrubs. Where soil piles up behind a retaining wall, plant creeping shrubs or flowers to spill over the edge and dangle down. There are many ways you can use retaining walls to function practically yet add artistic excitement to your garden.