The first tool I bought as a novice gardener was a carbon-steel hori hori, or Japanese digging knife, just like the one from Hardwick & Sons. Practically indestructible, mine (pictured) is still poking holes in my back pockets thirty-odd years later. It has proved sturdy enough to penetrate stony soil and can unearth taprooted weeds. The serrated edge makes quick work of dividing plants as well as loosening pot-bound plants. It cuts through fibrous, tuberous, and circling roots like butter. Over time, when wiped clean and dry after use, the carbon steel becomes polished and silky, and the wood handle develops an oiled smooth finish from being handled.