What Are Thrillers, Fillers and Spillers?

Patios and outdoor rooms require careful planning and design choices when there is limited space for plants. While there is no hard and fast rule for container gardens, the popular concept of thrillers, fillers and spillers has made it easier to approach the design task of which plants to put in a pot. The idea is based on the theory that an odd number of plants -- three is a good number for an average-sized container -- looks natural, well-balanced and interesting.

A thriller plant is one that is usually tall or dramatic looking, and is positioned at the back and center of the container. Examples of thriller plants include:

• Ornamental grasses
• Gaura
• Coleus
• Cordyline or Dracena
• Tall-growing succulents

A filler plant might be obvious, but it's one that fills out the container, making the arrangement look lush and healthy and filling the middle space, in front of or surrounding the taller thriller. A couple of filler plants can be used and should be planted between the thriller and the spiller. Examples of fillers include:

• Lantana
• Nemesia
• Coleus (a different color and shorter than the thriller variety)
• Calibrachoa (Million Bells)
• Midsize succulents
• Euphorbia graminea
• Begonia
• Heliopsis

The spilling plants are trailing types, that spill out of the container and are planted at the edge of the container. Spillers include:

• Verbena
• Petunia
• Sweet potato vine
• Torenia
• Trailing or spreading succulents