A hori-hori is a Japanese multi-purpose gardening tool. They were originally invented by foragers to carefully excavate sansai (mountain vegetables).
Also known as a “weeding knife” or a “Japanese gardening knife”, it has a sharp blade for cutting through tough roots or stems. The blade is also concave to act as a trowel, has a serrated edge to act as a saw, and often has markings to be used as measurements (for example, to measure how deeply bulbs are being planted).
Gardening knives can have sizes anywhere from 4.5 cm to over 17 cm. A hori-hori can be a very useful addition to any serious gardener’s toolkit though, as always, care should be taken with sharp gardening tools.