and a pair of wire snips.
Snip off the “shoulder” corners of the hanger where the wire bends up into the “collar” area of the hanger. Then snip through the bottom, flat section of wire at about the same distance in from the corner as your top snip was made.
You’ll get a piece that looks kind of like an airplane wing.
Use the wire snips to bend the wing into a classic staple shape. Adjust the width of the staple according to what you need to secure in the ground. If your estimates of length were wildly off, trim the ends with the snips or re-bend.
Garden staples are infinitely useful. Use them to hold down plastic or paper mulches, landscape fabric, soaker or drip irrigation hoses, or individual plant cloches cut from milk jugs or soda bottles. They are also great for pinning down plants that you are propagating thorough layering.
You can buy garden staples, of course, but in my experience the DIY hanger ones actually work better. The coating on the wire keeps them from rusting away to nothing as the store-bought kind tend to do after a few seasons. You can also adjust the height and width depending on your need. And if you happen to have the white coated hangers, staples made from those are much easier to find in the garden. Plus, they’re free!