When creating a container or a landscape, you can use the horticulturally trendy mnemonic phrase, “Thriller, Filler, and Spiller”, to determine your plant palette and the number of plants you need.
For containers, visually divide the finished height by thirds. One third is the container, two-thirds are the plants. You can have a larger container that is two thirds and one third is the plants but be careful in choosing appropriate species.
For landscapes, divide the entire area/bed by thirds. One third is the ground area, and two-thirds are the shrubs and tree.
Thriller: One exciting plant or tree species, horticulturally known as a specimen plant.
Filler: For containers, it can be one or two species, or color variations, with three to five plants. The number is determined by the size of the container. For landscapes, the fillers can be a medium-sized shrub, one or two species that complement each other.
Spiller: To add depth, add three to five plants that hang down, it can be one or two to three species. For landscapes, it’s the groundcovers, plants that are small in height but can spread over an area. Add two or three species for color and texture variation.
Make sure all the plants are compatible for mature size, sunlight, soil moisture, and pH conditions
For added interest in a container, the “Thriller” can be a piece of art, signage, or statue. In the landscape, the taller “Thriller” could be garden art or a water feature. Let your imagination bloom!
