The first ingredient is an attention-grabbing plant, also called a thriller. This plant takes center stage in a container, serving as the star of the design production. All other plants relate to this player in some way. Usually the thriller plant features an in-your-face shape with a strong upright growth habit. Thrillers typically unleash flower power by blooming nonstop all season, or they unfurl dramatic leaves. In containers viewed from all sides, place a thriller in the center. In containers placed against a wall, position it in the back.
The second ingredient, known as the filler, complements the thriller, but it never steals the spotlight. These supporting players typically have rounded mound or misty shapes. Fillers accomplish several tasks. They complement the thriller with leaf or flower color, texture, or other special characteristics. They help disguise the thriller's base and add colorful substance in the space between soil and thriller. Aim for fillers that grow to one-third to two-thirds the height of the thriller. Place fillers around the thriller between it and the pot rim. For a pot that looks instantly full, use three fillers in a 14-inch pot. If you're willing to let plants slowly fill in, you can plant just two fillers: one in front and one in back, or, if they are in pots that will be in a corner or against a wall, one on each side of the thriller.
The third ingredient is a plant that trails over the edge of the container and helps tie it to its surroundings. It's called a spiller plant. When you're looking for a spiller, seek a plant with a sprawling shape. Leaf or flower color should contrast or echo that of the thriller and/or filler. Plant spillers along pot edges in the openings left between filler plants. It might be a tight squeeze, but feel free to shove and shoehorn plants into place. Anticipate using two spillers for a 14-inch pot viewed from one side, or two or three spillers for a container viewed from all sides.
Get inspired. Look for container ideas in plant catalogs or garden magazines. Choose colors that match your outdoor furnishings or your home's exterior. Or simply find a plant you like, and build a custom design around it. Test it out. Give your design a dry run at the garden center. Arrange plants in your cart the way they'll appear in the container. Change as needed. Scale is relative. A plant used as a filler in one pot might make a nice thriller for a smaller pot. Typically, a thriller should not be taller than two times the height of the container. Think texture. Mix leaf and flower textures in your container gardens to create the most beautiful designs.
Find inspiration for your container designs in these classic combos. You don't need to exactly duplicate what's shown. If you like the color scheme, feel free to use different plants to produce that look. Be creative and adaptive, selecting plants that inspire you.
Black-eyed Susan serves as a thriller, Dragon Wing begonia and 'Buddy' Gomphrena as fillers, and silver thyme as spiller.
Pink-and-green caladium is the thriller, Infinity Pink Frost New Guinea impatiens is the filler, and variegated ivy is the spiller.
Elephant's ear towers as the thriller over orange impatiens, which act as both filler and spiller in this combination.
A low thriller, deer tongue fern, is surrounded by 'Dark Heart' coleus and Alternanthera serving as fillers and spillers.