Cedar lumber is an excellent material for the construction of raised garden beds due to its natural decay-resistant characteristic. What you choose to fasten the boards with is equally as important to their longevity and appearance.
The Western Red Cedar Lumber Association advises using nails or screws made of stainless steel, aluminum or hot-dipped galvanized steel that resist corrosion. Electroplated steel and copper fasteners are not recommended, as they will deteriorate over time and leave unattractive stains. Choose a nail or screw length to allow at least 1½ inches penetration into the piece being joined. Ringed or spiral nails and screws hold better than smooth nails.
Drive nails in an alternating pattern, not a straight row, and blunt the points first to avoid splitting the wood. Drilling a pilot hole of a smaller diameter than the screw also helps prevent splitting.
Reinforce joints by driving fasteners through the boards into a wood block placed in the corners, or attach galvanized metal corner-braces. Join layers of boards with galvanized metal joining-plates or fasten boards vertically across layers to make taller beds.