I am working on pot- scaping in my garden. At a recent gardening symposium, I learned to make potted plants interesting by mixing together a variety of plants. You want first to add a focal plant that has the height in the middle of the pot. This is called the thriller. A pencil post holly or boxwood works well here as it stays evergreen throughout the year. These typically only can stay in a pot a couple of years as they will outgrow the pot and need to be transplanted. A dwarf ornamental grass would work well here also. There are some pretty red fountain grasses available at plant nurseries.
Secondly, you want to add plants to fill the pot or the fillers. A mixture of colors and textures are good to fill in. You might add some flowering plants as well as plants with interesting leaf textures for continued interest throughout the season.
Lastly, the spiller is plants that cascade down the edges of the pot. There are a lot of these to choose from in flowering forms. You could choose a “wave” petunia which come in a wide variety of colors. For interesting foliage or contrast I like creeping jenny or sweet potato vines for a shot of Chartreuse. There is a red potato vine as well. Ivy or Vinca vine are commonly used also.There are some pretty variegated green and white species that are stunning in pots. Any plant with white coloring adds a pop to a pot.