Select a site that receives full sunlight, good air circulation and good drainage.
Remove any existing vegetation by applying herbicides or cover the area with clear plastic sheeting. Leave the sheeting in place for one to two months to ensure all vegetation is killed.
Lay out the garden bed perimeter with stakes and string. Drive in a stake at each corner and run string between the stakes.
Attach a line level to the strings and ensure all four sides are level.
Excavate a trench along the inside of the string, approximately 8 inches wide and 6 inches deep.
Place garden soil inside the trench and use a flat-nose shovel to level.
Ensure the trenches are correctly leveled. Place a carpenter's level on a length of 2-by-4 and set it into the trench. Fill with sand, soil or gravel and tamp down to even out the soil level.
Lay the first course of landscape timber into the trench. Place each timber so the corner overlaps the end of the adjoining timber. Check for level and drill two holes in each end of the timber slightly smaller than the diameter of rebar being used. The size will vary according to the type of rebar used.
Drive two lengths of rebar into each end of the timbers at 20 degree angles to the center. Ensure each length penetrates at least 12 to 18 inches into the soil.
Lay the subsequent courses of timber in an overlapping fashion, securing each timber into place with galvanized landscaping spikes. Use two to four spikes per timber.
Place the timbers so the end of each overlaps the seam of the course laid underneath it, similar to the way Lincoln logs are stacked. Set each course directly on top of the one below it without any setback.
Ensure each timber is level as it is laid into place.
Place, drill and spike remaining timbers into place, until the desired bed height is reached.
Fill the completed bed with garden soil. Sandy loam is best for many vegetables and ornamental plants.