Terracing is a great way to take a steep slope and turn it into an area suitable for landscaping. Also called retaining walls (since they "retain" soil behind them), terracing adds interest by introducing textures from different materials and allowing a homeowner to create a variety of spaces for different activities.
Whether you have existing terracing or you're thinking about adding terraces, you might be wondering what kind of design or planting options make the most sense.
Create an outdoor room
If you have multiple terraces, one design option is to create an outdoor room. If the space above the terrace is level, you can add a patio area to take advantage of a view or add space for entertaining. This view can be a mountain, a special tree in your neighbor's yard, or even a different view of your own home. The point is to have something to see from your new space.
If you are adding a retaining wall, consider designing the wall to include seating on the level side. Informal seat walls are an attractive and space-saving way to provide extra seating for entertaining guests.
Check for proper drainage
As long as your retaining wall has proper drainage, planting behind the wall should not be a problem. Check to make sure there are weep holes or drainage pipes at the bottom of masonry walls. Keep in mind, however, that if your water is high in minerals, such as calcium, leaching through masonry walls will create unsightly staining.
Retaining walls made of landscape timbers or railroad ties will last a long time if the wood is properly treated; but eventually you may need to replace the lumber. This might present a problem if you plant large trees or shrubs species behind the wall, as their root systems will be compromised during the replacement process.
Vines: Planting vines behind your retaining wall is desirable if your goal is to soften the hard vertical lines or if your wall is unsightly. Make sure you select the right species for your climate, and one requiring the least maintenance. This means avoiding plant species with winter dormancy or those requiring regular pruning. Avoid vines that have aggressive aerial rootlets, such as Boston or Algerian ivy . These can damage mortar between bricks and blocks.
Arching plants: Another option is to add plants with an arching form. The tombstone rose and trailing rosemary, for example, create a large informal mound that's perfect for hanging over a retaining wall. Since it does not trail or vine, it will not work its way in between mortar or wood timbers.
Grass: While planting a lawn behind your retaining wall is an option, make sure you allow adequate access for maintenance such as mowing. Keep the area small and easy to manage.
An alternative to a high-maintenance lawn is planting native grasses and wildflowers. Going native is a current trend toward sustainable landscaping, requiring minimal water and avoiding the need for non-environmentally-friendly fertilizers as well as pest- and weed-control chemicals.
Linda is a landscape architect and certified arborist in southern Arizona. With over 20 years experience in landscape design, she also has a passion for all plants and gardening. As a freelance writer for a number of websites, she has produced hundreds of articles on plants, plant care, and design.