Harvesting garlic scapes is a simple and very easy task. Grab some small clippers and then head out into the garden. Make sure you have harvested it before it has sprung its flower. Also make sure you cut it before the scape has curled around (at the top of the scape and where the flower will form), it tastes better and is nice and tender. Locate the scape and make a small mental note on where your going to cut it. The best location to do that is, as far down as the last set of leaves (near the top). One side suggestion is to cut it in the afternoon so the sap dries up quickly, so that it isn't as vulnerable to disease.