How to Make Stairs in a Sloped Garden

Design the stairs. Measure the length of the stairway space with a tape measure to determine the number of treads needed. Figure the angle of slope by putting a stake at the top and a taller stake or pole at the bottom. Stretch a line with a line level between the two and measure the distance from the ground to the line at the bottom to get the fall of the slope. Divide those numbers by tread and riser space; allow 6-to-9 inches per riser and 12 or more inches for treads; gentle slopes can use shorter risers and longer treads.

Mark the outside edges of the stairs with stakes and mason's twine. Allow at least 36 inches in width for most stairways; narrower ones will accommodate only one person comfortably. Mark riser locations; use spray paint if you want. Dig out the stairway with a shovel to the depth of the stone being used plus 4 inches, forming the dirt into step elements the proper width and depth.

Put boards across the stairs at riser locations for temporary braces on a steep slope or if you are using cut stones in a regular pattern. Tamp the earth with a hand tamper to compact it and add about 2 inches of small gravel, also compacted. Top the gravel with 2 inches of mason's sand, also compacted. Use a level to get the sand level both up and down and side to side. Put black plastic down along the stairway before adding gravel if weeds or grass will be a problem.

Start building stairs from the bottom. Begin with a big flat landing, either one solid slab or stones set in place individually. Build the first step to overlap the top end of the landing. Set individual big slabs in place and level them with a level by adjusting the sand. Build steps with individual stones by setting them in the sand; with cut stone, set the riser stones first then add stones behind to the next step. Remove the temporary board braces and work your way up to the top.

Test the steps by walking them a few times. Look for any loose stones that wobble when you step or are out of line and might cause tripping. Adjust any bad stones; replace individual stones if they cannot be set solidly. Finish the steps by sweeping sand into joints between steps and filling dirt around the outside edges after removing the marker lines.