I let them grow almost everywhere. Another way to bring back a little nature is to make a pond. Notice the bio-diversity with both planted and naturally sprouting plants. Some of the planted plants I transferred from the wild and they have flourished. There are so many frogs in this pond that I now have a predatory, frog-eating bird visiting it regulrly.
Frogs love all of that green stuff.
Just ask this guy, or one of his hundred or so buddies that call my little pond home.