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A No-Fail Formula for Designing Beautiful Containers

By: Garden Gate staff
Does your container garden fit this formula? If you need more pizzaz, it’s not too late to use these tips for gorgeous containers!


Create a knockout container

Designing containers doesn’t have to be complicated. If you’re looking for an easy way to put together amazing looks every time, simply remember three rhyming words: thriller, filler and spiller. Let’s define each:

  • Thriller

    Upright, tall-growing plants with striking shapes are thrillers. Just like the vibrant pineapple lily in this group, they add interest and excitement.
  • Filler

    Fillers have more rounded, mounding habits that work to fill in the height gap between thrillers and spillers.
  • Spiller

    Spillers are the low-growing plants that drape over the sides of your container. They’re great because they hide the lip of the pot, softening the hard edge with flowers, foliage and color.

Browse our best container recipes and tips


How to design a container garden with thrillers, fillers and spillers

Now which goes where? After you pick out plants that thrill, fill and spill, the rest of the design falls into place quite easily. Here’s a rundown of how to plant your container:

Step 1 - Plant the thriller

The thriller is usually the biggest plant, so keep things easy and plant it before the others. Center the thriller right in the middle of the pot, especially if it will be placed on a patio or somewhere where it will be viewed from all sides. But, if you plan to position it up against a wall, place the thriller in the back so that all the rest of the plants can be seen from the front.

Tips for choosing a thriller:

  • A flowering plant or a foliage-only plant both make great options. If you choose a flowering plant, choose something that will bloom all season long. If it doesn’t have a long bloom time, be sure that the foliage will be interesting enough without the blooms and that the plant will maintain its tall stature in the center even after the flowers fade.
  • For a standard round container, you usually only need one thriller. For long rectangular planters, you will likely need more than one.
  • Don’t feel limited to just annuals. Perennials, shrubs and even tropicals and house plants can make wonderful thrillers that can be used elsewhere in the garden later, too.
  • Choose a height that balances the size of the container. A good place to start is with a plant that is the same height as the container (so that when planted the total height of the container garden doubles). But this isn’t a set rule. If you choose something taller than this, make sure the container can support the weight and won’t tip over easily, especially if placed in a windy spot.
  • Don’t forget to leave room for the other plants. Something that is as wide as your container is probably too big and will end up outcompeting the other plants.

Step 2 - Plant the fillers

Fillers are the plants that bridge the gap between the thriller and the spiller. They are just as important as the other plants, but probably won’t be the center of the attention. Before planting, keep them in their pots and arrange them around the thriller to get an idea of how to distribute them. You can also tuck the spillers in at this point, too, in order to be sure they all fit and look good together.

Tips for choosing fillers:

  • If you are using a foliage-only thriller and foliage-only spillers, make sure your fillers have long-lasting flowers.
  • Because a filler’s main role is to bridge the differences in height, be mindful of how big it will grow. Coleus (Plectranthus spp. and hybrids) are great fillers, but they can often overtake the container if they aren’t regularly pinched back. If your filler might grow too big, make sure it will still look good even after being pinched or cut back.
  • Pack them in! It’s surprising how many you can actually fit in order to give a container a full, flowery appearance.

Learn how to choose the right number of container plants

Step 3 - Finish with the spillers

Spillers are what give a container that unbeatably lush and lovely appearance. They soften the look of the container itself by hiding the edge. You may need more than one plant here, depending on how the container will be viewed.

  • Go for balance. If the plant will spill all the way to the ground, you might need more than one.
  • If a spiller starts to grow out of bounds, don’t be afraid to cut it back. Sometimes spillers get leggy and trimming them will give them a fuller appearance again.
  • Plants that clean themselves will cut back on work and keep your container looking good at all times.

Meet 8 of the best container plants


Container recipe (number to plant)

A) Pineapple lily (Eucomis ‘Aloha Lily Leia’) (1)
B) Petunia (Petunia Sun Spun® Silver) (5)
C) Calibrachoa (Calibrachoa Superbells® Grape Punch) (1)
D) Bugleweed (Ajuga ‘Pink Lightning’) (1)

Container shown is 16 in. in diameter


Product Recommendations

Here are some supplies and tools we find essential in our everyday work in the garden. We may receive a commission from sales referred by our links; however, we have carefully selected these products for their usefulness and quality.

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