Next, prepare eight 2-inch by 4-inch by 24-inch wood stakes. Drive a small nail into the broad (4-inch) side of each stake, four inches from the top.

Figure 2. Both A and D stakes should be driven to the same height above ground (not the same elevation), with the height determined by the height of the beds. Because the site is sloped, A and D will be at different elevations. To insure a uniform slope across the plot, use a leveling instrument to level A and B stakes with each other and C and D stakes with each other.

Locate the stakes 18 inches from each corner, centering them on each boundary line. Drive the stakes into the ground only a few inches at this time. Make sure the stakes are oriented with nails facing away from the plot.

Select one stake and drive it to a height above the soil surface equivalent to the height of the bed. For example, if your choice is rubber lumber or plastic mesh, set the stake 8 inches and 6 inches above the soil surface respectively. If you want to construct corrugated sheet metal beds, set the stake 14 inches above soil surface.

Use a surveying instrument and leveling rod to establish the remaining stakes at the same elevation as the first. An alternative method, although less accurate, is to use string lines and line (bubble) levels to set the other seven stakes level with the first.

Some sites have too great a range in elevation to try to level. If this is the case with your site, refer to Figure 2 for details on preparing a plot on sloped ground.

Drive the first stake to a height equivalent to that of the bed; "fine tune" the position of boundary lines with the use of a level; and designate the location of each boundary line on stakes with a waterproof marker.

Next, establish the exact position of each boundary (perimeter). Attach strings to the nails on each stake, making sure strings run over the top of the stakes. Be sure each string line is taut.

Use a carpenter's level or plumb bob to position each string line precisely above the nail points. Mark the position of each string line on the top of each stake with a marker or pencil. Mark both sides of the string. If a string breaks or you need to remove the strings prior to bed construction, they may be reattached to their exact location using the pencil marks.

Congratulations! You have now defined the exact perimeter, or boundary, and bed elevation of your raised bed plot.