A common way to design container gardens is by using plants designated as thriller, filler, and spiller plants. Thinking of container plants this way is particularly helpful for beginners and for anyone to get started in designing exciting plant combinations without getting intimidated by all the choices out there.
Thrillers, Fillers, and Spillers
First, a word about thrillers and fillers. Thrillers are generally taller plants and are often used in the center of design; they are like the focal point. The fillers are the plants that fill in the middle; these are usually between the pot and the thriller and may be a mounding plant that adds texture. Then, there are the spillers.
The spillers actually spill or cascade over the sides of the pot. They are usually placed closest to the rim of the container so they will tumble out of the pot. Spillers can be flowering or foliage plants and can be used to add a pop of color or texture that can be a counterpoint to both the filler and thriller plants. Spillers can be as thrilling as thrillers and can even be used in a pot by themselves.
Types of Spillers
There are many types of plants that can be used as spillers. Some are annuals, some perennial, some are chosen for their foliage and texture, others for flowers and color. And, some spillers are edible like oregano and some types of thyme.
Sweet potato vines are classic spillers. They come in a wide array of leaf shapes and sizes and colors from bright to almost black. Another common flowering spiller is lobelia. Its frothy blue flowers add both color and texture.
Ivies make great spillers. They are a somewhat structured plant and can be used to give texture, draping down the side of a pot.
While you can use one variety as a spiller throughout your pot, it is often effective to alternate, two or if your pot is large, or even have three varieties of spiller plants.
Also, some plants can be both fillers and spillers—if they are mounding and trailing—verbena, bacopa, oregano, and some varieties of sedum.
Foliage Spiller Plants
Flowering Spiller Plants
While the design concept of thriller, filler, and spiller can be helpful, it can also lead to container gardens that all look the same and formulaic—that one tall plant in the middle, surrounded by fluff, and then something spilling. If your entire garden is made up of containers, do not use this technique for everything. Design your garden to have a section that uses the thriller, filler, spiller formula, but then do something different in another section.
For something different, you can think of the group of containers like a class picture. You can place the grandest and tallest container towards the center-back of the group, the middle-sized containers can be surrounding or in front of the large thriller, and the smaller containers with spiller plants can be in the front and cascading to the ground.