Building a raised bed does not have to be expensive or complicated. You build a raised bed cheaply and simply.
Step 1: Identify a location for your garden.
If you are just getting started gardening, then you will need to evaluate where your yard gets sun and where it does not. A lot of the traditional garden crops (tomatoes, peppers, cucumbers, melons, etc.) like full sun, so picking a place with 8+ hours of sun a day will be important to make sure your garden is as successful as possible.
Step 2: Get the Lumber
For the most resilience pressure treated lumber or cedar are the best options to build a raised bed; however I like to use common board sometimes just to minimize my initial cost. This does mean that I am going to be replacing my raised bed garden sooner than I would had I upgraded my lumber upfront. You can make a garden be any size, but I would recommend making it no wider in any spot than about 4 feet. This gives you the ability to reach into the bed from either side without having to step into it. I chose to make mine 8′ x 4′.
I would not recommend using lumber any thinner than 1 inch for making your raised bed. At 1′ or more the bed should be sturdy, and at even greater thickness it can double as a shelf or stool for your garden. You then want the bed to be deep enough to allow strong root growth above the native soil. I am using 10″ wide boards. If you are disabled, or just don’t like the idea of bending over a lot in the garden, you can make your raised beds even deeper by raising them 2.5 – 3.5 feet above the native soil.
Step 3: Screw the Boards into the Rectangular Frame of the Raised Bed Garden.
A decking screw or wood screw works well here; however, even a drywall screw will get the job done.
Step 4: Put Down Some Cardboard
You can obviously do this step before making the raised garden bed, but I like to have the frame built so I can better visualize the area into which I am laying the cardboard. Make sure your cardboard sticks out into the walkway on all sides of your garden bed, this will cut down on weeds growing up right along the edge of your raised bed garden.
Step 5: Fill your Raised Bed with Soil
Many people will recommend “Mel’s Mix,” which contains equal parts compost, peat moss, and vermiculite. The goal is to have loose well-drained soil but that does not dry out to readily. I grow in my raised beds with straight compost covered in leaves or wood chips, and it also works well for me.