Decide on a color scheme harmonizing or contrasting with the colors of your house. Choose pastels for a shady area or bright colors for a sunny patio. Try a textural mix of silver-leaved plants, black plants or evergreens.
Pick plants with a variety of colors, textures and shapes. Use one tall, thin plant, such as a dracaena, along with midsize flowering plants and low trailers. Choose a bold plant, such as a canna, and surround it with wispy plants, such as baby's breath or Diamond Frost Euphorbia.
Take your container to the nursery and arrange possible plant combinations there. Choose something eye-catching as the centerpiece thriller and add fillers that pick up its colors. Arrange spillers such as lobelia, million bells, petunias, alyssum or lysimachia around the edge.
Select plants that have only begun blooming or that many buds. Remember that the plants will grow and change during the season, so don't choose something that will take over the container, such as ribbon grass or bamboo.