If you asked me what item every gardener should have I would excitedly exclaim “a Hori-Hori stainless steel weeding knife of course”! This one tool has literally replaced ALL of my other garden hand tools.
Smart Design
Traditionally used in Japan to collect specimens for bonsai (hori means “digging”), the knife has a heavy steel blade that is dished, with a serrated edge on one side and a sharpened edge on the other. It’s also got handy inch markings on the blade making it quick and easy to create your trenches and plant things at the right depth.
Stays Sharp
The one in this picture is over four years old now. Its still sharp after daily use through the summers. It also lived a whole winter under the snow in the pig pasture. 
Many Uses
We use it for a lot of different things including: planting, transplanting, grubbing, removing roots or deep-rooted weeds, dividing perennials, cutting open feed bags, cutting twine and impaling slugs.
Great Price/Value
You can buy a good Hori Hori knife for around $35-40 CAD. We got one of ours at Lee Valley and our second one on Amazon. Both have lasted an equally long period of time (6 years at the time of writing this). You can find it on amazon here. (affiliate link). Wherever you buy it make sure you get an authentic model with a stainless steel blade. I think this is a bargain especially for something that’s going to last years!
Tip: The wood handle camouflages itself really well in nature. Paint the handle or tie something bright to it. I have lost mine several times only to discover that it was “right there”.
Thanks Charlotte, sounds super interesting. When I click on your affiliate link it brought me to amazon dot COM though, not CA. Just a heads up, feel free to delete these comment when you figure it out. – John
Thanks for the heads up John and my apologies for the inconvenience. Amazon is a bit of a complex beast. It should be fixed but I’ll drop the Canadian link here as well: http://amzn.to/2sQ6S7A