Step 1: Plan Out the Area
It is critical that you consider climate, weather habits, maintenance, sun exposure, growing season and soil type when deciding what plants to buy. You can save money while your plants grow, knowing that your backyard is a work in progress and more plants can be added later. When designing your outdoor living area, don't forget to plan for lighting. Well-placed lights can make the area safer for evening entertaining, as well as create a great atmosphere. Be sure to design your outdoor space to compliment the house, especially if it is attached to it.

Step 2: Prepare the Soil
Break up the existing soil using a rented ground tiller. Next, add a new layer of composite soil using a wheelbarrow. Then, return to the tiller to mix the two soils together. With the soil prepared, place plastic edging along one edge of the yard to help contain new soil and rocks.
 

Step 3: Construct the Planter Boxes
Build new in-ground planter boxes using redwood planks, cut 4x4 posts and leftover composite decking.

After measuring off the deck and digging trenches with a pick axe, set in the completed sides of the planter box and use wood screws to join the two pieces. 

Give the planter boxes a finished look by screwing down two mitered cap boards formed using the leftover composite decking. With the planter boxes secured, backfill them with new soil.