I love garter snakes...I have a couple living in my gardens. One in the compost pile and one on the fence line.
If you have a healthy garden they will just show up. I have tons of frogs, another fav food of theirs, thanks to the pond. Toads are also a sign of a healthy garden.
I leave a lot of garden debris (leaves, small branches, etc.) in the gardens and they love winding amongst that kind of stuff.
