A post hole digger is a tool designed specifically for digging narrow, deep holes for fence posts, gate posts, deck footings, and planting trees. Two principal types exist: manual clamshell diggers and auger-type diggers.
The manual clamshell digger consists of two hinged, concave steel blades attached to long handles. The user drives the closed blades into the ground, then spreads the handles apart to close the blades and trap soil within. The tool is lifted from the hole and the handles are squeezed together to release the soil.
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This type is most effective in loam or sandy soils. Rocky or heavily compacted clay soil dramatically reduces performance.
A one-hand post hole digger combines a clamshell digging mechanism with a single handle and a foot-powered lever. The design allows the user to operate the digger with one hand while holding the post or performing another task with the other.
A manual auger consists of a spiral screw-like blade mounted on a vertical shaft with a T-handle at the top. The user twists the auger into the ground, and the spiral lifts soil to the surface. Manual augers are most effective in loose, well-drained soil.
Proper technique begins by marking the hole location and removing any surface sod. The digger blades are driven into the ground by lifting and dropping the tool (clamshell) or by twisting (auger). In clamshell digging, the user stands directly over the hole, drives the blades in, pulls the handles apart, and lifts. The extracted soil is placed on a tarp for easy backfilling. Deep holes require periodically removing accumulated soil from around the hole perimeter.
In rocky soil, a digging bar or crowbar is essential to loosen rocks and break through obstructions before using the post hole digger. Sharp-edged rocks can damage digger blades and ding the cutting edges.
After use, soil should be washed from the blades and hinges. The pivot point should be lubricated with light oil to prevent binding. Blade edges can be sharpened with a file to maintain cutting performance. Rust should be removed and the blades wiped with oil before storage.