Lots of flora will grow nicely in the shallow troughs of gutters. Small-root plants, annuals, and vines will flourish nicely. Various herbs like thyme, basil, sage, peppermint, and spearmint are also popular choices for gutter gardens. Or you can grow your own produce such as strawberries, lettuce, spinach, radishes, and onions.
Here's a step-by-step process on dressing up your fence with gutter gardens: