Creating a terraced garden can be satisfying work, and will give you an elegant garden. You can take a sloped backyard or hill area and layer it into tiers to plant whatever you'd like to grow. Building supporting walls can be done from bricks, pavers, concrete, rockery or timber. It's a matter of personal choice, in addition to what your budget can handle. Small terraced gardens can be built in a day, while larger ones can take several days or a week depending on size and styles. If you have plenty of room, leave space for a walkway along one edge or up the middle.
Contact your local utility departments to find out if you have any submerged electric cables, or other cables in the area you want to build the garden. Resolve any concerns so you don't inadvertently cut wires.
Plan the garden. Decide if you want to grow flowers, vegetables, shrubbery, trees or a combination of many types. Draw out a rough plan on paper, keeping in mind what will create shade, what you'll want easy access to, colours and blooms you might want to stand out in particular seasons, etc.
Measure the height of the area (rise) and the length (run) you plan to build on. If the length is 6 m (20 feet), and the height is 2.4 m (8 feet), you can build four levels that are each 1.5 m (5 feet) wide and 60 cm (2 feet) high.
Start at the bottom of the slope and rough out the beds. Dig a trench at the bottom front edge of each level, and along each side. Dig the soil out to shape the beds, using extra soil to fill from the back of each level to fill in the forward area.
Lay in your drainage pebbles and any piping at the bottom of each layer, along the front edge where you dug the trenches. Continue to lay drainage along each level at intervals of about 1.8 m (6 feet) and along outside edges.
Set the supporting walls. If you are using rocks, stack the rocks in front of each level to the desired height - 2 feet in our example. Arrange them so they are firmly in place. If you plan to join them with cement, make sure the wall has dried before standing on it or continuing. If you are using treated timbers (not for vegetable gardens), line them along the front of each layer and join them with bolts as needed. Stacking too many too high can result in an insecure wall. The timbers can be dug in and partially covered with soil so that about half of each timber actually shows. Try to shape the wall (rock or timber) so that it leans slightly in toward each level - this prevents it from falling forward.
Dig the holes for the trees, shrubs and flowers. Have your hose handy. Plant each terrace level according to your design layout. If you are only planting vegetables, place the seed so any vines won't overtake or shadow low growers. Make sure to leave room to move through the plants for weeding.
Water in all the plants and add about 5 cm (2 inches) of mulch around them. On the first watering, make sure you water everything in well. If you notice sunken areas that collect water, add a little soil to level it out. If all the water collects at the front of any level, you may need to add braces a few feet apart along the front edge on timbers, or make slight revisions to rock layout. This is usually not an issue, but you do want to check, especially if you want a strong wall that will stay in place.
You can add additional drainage by drilling holes and adding slender piping sections to the front of timbers every couple of feet. If you have children, secure each wall section carefully, but discourage them from walking directly on top of them. If the height of each of your terraces is only about 30 cm (1 foot), you can easily use large rocks to create beautiful walls. Don't put heavy rocks on top of poor quality, lightweight draining materials -- this can possibly crack or break them if the rocks slip and you may have to redig.
Growing vegetables where toxins can run off treated woods is unwise and harmful to your health.