Some years ago a friend gifted me a tool I have never stopped using. It is called the hori hori. Often people see it in my sheath and think I have some crazy knife–and that is pretty much what it is: a soil knife. They handle better than trowels and because they are sharp on both sides, are great for doing almost anything you need to do in the garden that you would want to do with your hands (in other words, not with a large tool like a spade or hoe).
Blades vary in length and width. Some are serrated on one or both sides, some are totally smooth. It’s all a matter of personal preference which sort you pick out. I have found the serration to be handy at times, especially for dividing perennials or bulbs. Blades are made most often of steel; the carbon steel blades are heafty, when you need heft. The stainless steel blades are lighter to handle, sharper, and don’t rust. Stainless steel hori hori soil knives are only slightly more expensive than the carbon steel versions.
The word “Hori” (ホリ) means “to dig” in Japanese and “hori-hori” is the onomatopoeia for a digging sound. It was originally designed for excavating bonsai plants from the ground. I get mine from Hida Tool (they have other fun toys too).