Terraced Garden Design Ideas
Creating a tiered or terraced garden, reminiscent of Italian and French gardens, is a time-honored way to transform a sloped yard into one with more usable space. A hillside that is converted into several broad level terraces will provide additional space for planting areas, pathways, or paved areas for seating and entertaining.
Many cities and counties have restrictions against homeowners building retaining walls higher than 4-feet. If the hillside requires a higher wall, consider adding an additional tier or terrace. Some communities will require a landscape construction permit for walls higher than 3-feet. It is a good idea to check with the building department before starting this kind of project.
Grading Slopes & Hillsides
Even well packed soil is not completely stable on steep slopes. If extensive grading is required to create the terraces, consider hiring a soil engineer or landscape architect to ensure the final terracing will be structurally secure.It is better to have more tiers or terraces that are lower than one or two that are higher and require additional bracing.
Wooden & Stone Retaining Walls For Terraced Gardens
If this will be a DIY project, it will save time to rent a gas-powered tiller. Tillers cut about 8-inches at a pass, and will make short work of excavating a hillside into tiers. There are a number of options for building retaining walls. Wooden retaining walls are the easiest to build with simple tools and are usually the least expensive. Use pressure treated lumber or wood that is resistant to decay, such as redwood, cedar, or cypress to delay rotting. Wood retaining walls constructed of 4 x 4 lumber should have galvanized spikes every several feet to anchor the courses of lumber together. Longer walls should also have staggered joints in the courses and overlap at the corners.
Stone and brick are other options for tiered gardens. These materials do require more advanced skills in construction. But with a little effort, anyone can do this as well. A dry stone retaining wall, which is a stonewall set without mortar, can be a thing of beauty. Start by digging a trench or foundation about 6 to 12-inches deep. Line the trench with landscape fabric and a gravel base. Then, begin laying the first course of level stones. Choose larger stones for the outer edges. Lean the wall slightly into the slope, at a slope of 2-inches for every foot of wall height, to give it stability. Install a perforated drainpipe near the bottom course to drain water away from the wall. Apply gravel to the backside of the wall to improve drainage.
Terraced walls constructed of poured concrete, brick, or block must stand on a concrete footing to make them stable. Retaining walls must be able to support the additional weight and pressure of tons of soil. They must be stronger than simple garden walls. Bricks and cement blocks should be set in mortar and begun on a cement foundation twice the width of the wall and dug into the hillside about 6-inches deep. There are many options for decorative cement blocks. Some blocks lock together without mortar. It is worth a trip to the building center to see what is available.
Drainage For Terraced Gardens
Whatever material you choose for tiered walls, good drainage is imperative for plant health and preventing soil movement. Even a well-constructed wall can fail if too much water builds up behind it. A properly constructed wall will have landscape fabric wrapped behind it, a perforated drainpipe near the bottom, and gravel backfill to improve drainage on the backside of the wall.
Plants For Terraced Gardens
Choosing which plants to use in a terraced garden is one of the most rewarding portions of the project. Decide on a theme for the new terraced garden: annual color, vegetables, herbs, shrubs, a fairies’ garden, or any combination of these. Combining vegetables and flowers in the garden is a popular theme. With a little imagination, vegetables and flowers in the same garden can provide striking results. And, they can provide a tasty harvest. For tips on growing a small spaced garden with maximum potential, see The Square Foot Gardening Guide.
Look for plants that can cascade over the walls such as nasturtium and trailing rosemary. Choose colorful summer annuals and perennials such as daises, marigolds, poppies, and snapdragons for instant color. Surround these with purple and blue-green vegetables like cabbages, leeks and kale that will continue to provide a colorful display through the fall and winter.
Consider the scale of the tiered garden when choosing shrubs. Keep them in scale with the other plants. Terraced gardens with ample shade also have the opportunity of choosing shade-loving ferns, perennials, woodland flowers, and herbs. See Shade Garden Design Ideas. Choose from balsam, feverfew, begonias, lily of the valley, basil, parsley, daylilies, meadowsweet and bellwort. Be aware of the local climate zone when choosing plants to insure the plants will thrive in the new garden.