Garden Dirt

Thrillers, Fillers, and Spillers – The Answer to the Perfect Container Design

(All photos: Greenstreet Gardens)

By Ray Greenstreet

Alexandria, VA – Assembling eye-catching container gardens doesn’t demand a degree in botany or art. You can mix and match plants with the best container designers simply by mastering a few tricks of the trade. By focusing on the main components of thrillers, fillers, and spillers, you’re guaranteed to create container gardens with eye-pleasing charm. Get ready for your best container gardens ever!


In container gardens, thrillers are the plant world equivalent of a showstopping diva, prima ballerina, or star quarterback. Thrillers earn top billing in a container, occupy the key spot, and capture attention with their botanical prowess. They hold court over other plants in the pot by virtue of their outstanding characteristics—showy, colorful foliage, striking season-long blooms, or bold, dramatic form.

Many thrillers introduce a strong sculptural element to a planter—like a banana plant, a variegated canna, or a New Zealand flax. This trio offers broad, often colorful foliage that issues a powerful statement in a container garden.         

Thrillers most often set the bar for height in a container, being the tallest plant in the mix. Over the course of the growing season, a filler may reach toward the thriller, or a spiller may climb and vine around a thriller, but from the start, the thriller sits at the top of the container ladder. Generally, thriller height shouldn’t exceed 1.5 times the pot height.


Filler plants play a supporting role in container garden drama. They’re the actors who play off and interact with the star thriller, adding interest and intrigue to the potted plant play. Fillers give a container a feeling of fullness, growing in billows to add mass to the planting blend. In essence, a filler surrounds, supports, and often hides the thick lower stems of the thriller.

Typically, fillers either complement the thriller, echoing the color palette with foliage or flowers, or strike a bold counterpoint, unfurling leaves or blooms in hues that contrast beautifully with the thriller. When the thriller offers narrow, upright leaves such as ornamental grass, a round-leafed filler like coleus or geranium spins an eye-pleasing scene.     

If you’re focusing on flowery fillers, choose types that bloom all season long. Good choices include impatiens, angelonia, begonia, or lantana. Fillers can also hold their own with outstanding foliage. Dusty miller, Persian shield, caladium, or croton fills this bill. Planting a mix of flower and foliage fillers can give your container garden a polished look, provided you choose plants that complement the thriller and spillers.


In the screenplay of container garden design, spillers are the background players, the cast members whose presence would be missed but whose characters remain unnamed. Spillers bridge the gap between container and earth, anchoring the pot to its surroundings, giving it an organic feel, a sense of connection to the landscape that encircles it.

These cascading plants echo the colors and textures already found in your thrillers and fillers while offering a contrasting look. An effective spiller may start a dialogue with a filler or thriller by reflecting a leaf form or flower hue found in these beauties. For instance, a trailing potato vine can showcase the dark leaf banana or alternanthera thriller. A white bacopa can intensify the interplay of a burgundy flax thriller and orange profusion zinnia and rose dianthus fillers. Use your spillers to play with the colors found in your container.

Count on spillers to underscore textural motifs in container design. The delicate, airy disposition of dichondra or sweet alyssum creates a stand-out effect with other broad-leafed fillers and thrillers in the pot. You can use a broad-flowered petunia to repeat the strong textural tones of a broad-leaf thriller.

Final Tips


Once you decide on the components of your container, it’s time to remember the other ingredients you will need. Gorgeous container gardens begin with good soil; choose a mix that’s light and full of air pockets, drains well but also holds water, and gives roots a boost of slow-release fertilizer. Every container needs a drainage hole so water can drain away from roots. If plants sit in water, roots will rot. And when you tuck plants into your soil, set them at the same depth they were in their original container. Planting too deeply can cause stems to rot. Look for additional tips to keep your new container successful at your local garden center.

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