Used as a landscape plant, a topiary adds a little extra character and charm to a yard. The carefully shaped tree, shrub or other kind of plant instantly gives a lawn or garden a decorative and polished appearance. Usually, a form is used as a guide for trimming a plant's foliage into a specific shape to create a topiary, but you also can make a striking version with climbing plants or clippings, choosing a look that fits your landscape to a tee. When you use tools to trim a topiary, disinfect them before you start, before you trim a different plant and after you finish trimming; doing so prevents the spread of plant diseases. Soak the tools for about five minutes in a solution that is one part 70 percent isopropyl rubbing alcohol and one part water, or soak them in a full-strength household disinfectant, and then rinse them with water.
Keep it Formal
Formal topiaries feature symmetrical, geometric shapes such as cones, cubes and pyramids cut into the woody plants. The plant choices for a formal topiary include boxwood (Buxus sempervirens), which is hardy in U.S. Department of Agriculture plant hardiness zones 5 through 8, English yew (Taxus baccata, USDA zones 6 through 7) and bay laurel (Laurus nobilis, USDA zones 8 through 10). Choose a plant that grows naturally in a shape similar to the shape you want to create. For example, select a plant that grows upright if you plan to create a cone. For a spiral topiary, opt for a plant with a single central stem. Using long-handled shears is necessary to trim the foliage, and a metal topiary form is needed as a guide so you know which and how much foliage to cut. Forms in traditional topiary shapes, including cubes, cones and circles, are available at many garden supply stores. If you want to create a spiral topiary, then wrap a piece of string around the plant to figure out the right areas to cut.
The same woody plants used for formal topiaries are used for informal topiaries, but the shapes of informal topiaries are more whimsical. They often feature animal shapes but also display heart and star shapes. When creating or trimming an informal topiary, use a metal topiary form because cutting freehand can be extremely challenging. As with a formal topiary, choosing a plant that has the same basic shape as the design you plan to create makes the project easier.
Let it Climb
Starting a topiary with a plant that can grow over a topiary form is simple. English ivy (Hedera helix, USDA zones 4 through 9) is an option that grows easily and will climb up and over a form; because it is invasive, though, English ivy needs to be contained to prevent it from spreading to other areas. Begin by covering the bottom drainage hole of a heavy terracotta or stone pot with a piece of panty hose or window screen, and plant the ivy in the pot with potting soil and a granular, 15-5-10, slow-release fertilizer, ensuring the ivy is centered in the pot. A pot with an 8-inch diameter requires sprinkling about 1/4 ounce of the fertilizer on the soil surface at planting time and every three months. Water the soil thoroughly after applying the fertilizer. The next task is to choose a topiary form that you like and secure it in the soil. Train the ivy to grow over the form by wrapping one of the plant’s runners, or vines, around a wire in the form. Wrap a second runner around the same wire, but wrap that runner in the opposite direction that you wrapped the first runner. Cover all of the form’s wires, using raffia cord to tie the vines to the form. Pruning the ivy as it grows is necessary to keep the topiary from losing its shape.
Using succulents to create a topiary is another method that doesn’t require cutting. The finished product resembles an evergreen topiary but offers a more unusual take on the look. Although any succulent can work, the rosette echeveria (Echeveria spp. and cultivars, USDA zones 8 through 11) is an effective option because its foliage features a variety of colors, including teal and pink. Start with a topiary form in your chosen shape, and line its interior with chicken wire to form pockets to hold the succulent. Fill the form with a mixture of potting soil and moss so it has no empty spaces. Placing the form in a decorative pot is an alternative, but filling the pot with sand or gravel first weights it. Stake the topiary form in the base material to secure it in place. Poke holes in the packed soil and moss with needle-nose wire cutters, and place cuttings from a succulent in the openings, securing the cuttings with florist pins. The succulent's leaves will eventually anchor themselves with roots to the moss and soil.