Terraced slope gardens are the province of old houses and non-prairie dwellers. Even "flatlanders" can have terrace gardens if their property is graded properly. New materials provide alternatives to the old railroad tie structures. Ideas for terrace gardens abound from classics like Monticello to more modern forms. All of these gardens capitalize on the water-retentive and sunlight-maximizing qualities of terraced slopes.
Terraces should be designed to correct a slope to retain water and optimize sunshine, but they also need to be built so that they can be mowed and maintained easily. Build grass terraces at least as wide as your mower and provide access along the sides of the walls. Build terraces with a 1 to 2 percent slope to keep water from sitting on the terrace or running down behind walls. Provide access to garden beds, either by installing walkways down the terrace with railroad ties, wide paths of mulch at the back of each level or by planting every other terrace in grass or some ground cover that will allow foot traffic. Sink wooden ties into gravel-lined trenches and join ties vertically with steel reinforcement bars drilled down through them; back-fill stone or cement block walls with gravel to provide more efficient drainage. Never use gravel to mulch, though--it allows the ground to heat up and weighs down soil, squeezing roots. Always contact utility companies to mark underground pipes and cables before beginning to dig to build terraces.
Plant terraces to maximize the use of sunlight; if the terrace is on a north-facing slope, plant tall or shade-loving plants on lower levels. Plant vegetable gardens nearest the house and use companion plantings to “camouflage” their utility. Organize gardens so that perennials are planted in the least-accessible spots; they will be easy to get to before annuals are planted in the spring and after they are gone in the fall. Plan your gardens so that they are vertical--up and down a section of the terrace--or horizontal--across one tier of the slope--for unity. Plant trailing plants like blue lobelia, wild geraniums or trailing verbena just behind the wall for informal color to complete your gardens.
Low Maintenence Terraces
Plant shrubs, native plants and self-regulating perennials for terraces that are simply utilitarian. Butterfly weed, for example, attracts butterflies but also chokes out weeds. Daylilies’ thick root systems are erosion-stoppers. Redosier dogwood provides winter interest. Xeriscape with redbud, lantana, purple coneflower or yucca and other succulents at home in dry environments. Use rain garden plants like American elderberry, cardinal flower, ferns and sedges where water is abundant. Plant native plants and wildflowers in their home environments to reduce disease and infestation by insects. Use organic mulches with wood chips or compost with well-rotted humus, to keep plant roots cool and reduce the need for water.