Window boxes are a blank slate for you to design and plant in. If you plant them right, the design options for a successful window box are endless.

By Miranda Crowell
June 06, 2019

Window boxes give gardeners an affordable outlet to do what they love most: experiment. Known as one of the first living walls, window boxes have been a longtime favorite of gardeners. Window boxes continue to be a popular landscape element today and often stand in for front yards at homes that open to the sidewalk. Although there is a lot of creative freedom with planting window boxes, there is a right way to do it. Window boxes show off the wide range of possibilities a few feet of soil can offer, so use our tips to create a floral creation of your own.

How to Plant a Window Box

The first step is to choose your box and where you want to hang it. Don't underestimate how heavy a window box can be—it is filled with soil and plants, and gets even heavier when watered. We recommend buying a sturdy box made of a hardwood like redwood or cedar rather than pine, which rots quickly, and then securing the box with a window box bracket like the Panacea Holdall Flower Box Holder, starting at $14.40, from Amazon.

Always make sure your window box has drainage holes. To aid drainage, place 2 inches of nonbiodegradable packing peanuts or old wine corks in the bottom of the box, and then cover with landscape fabric to prevent soil from seeping out.

Next, fill the box halfway with potting soil, and add your plants. Make sure your plants are placed a few inches apart to give them room to fill out. If you want immediate impact, you can plant closer, of course, but know that you will need to pinch or prune your plants to prevent overcrowding. Once your plants are in place, fill in the gaps with more soil and lightly pat down around the plants.

As with all container plantings, choose plants with similar water and light needs, and expect to water them more often than those in the ground. Water thoroughly once the soil has dried out.

Selecting Plants for Your Window Box

Most successful window boxes contain a mix of these three primary plant types. These are some of our favorites in each category.

Thrillers

They are your hero plants—the ones that command attention and drive the rest of the design.

  •  ‘Katrina’ African iris: Exotic flowers top long, spiked leaves.
  •  ‘Sallyfun Deep Ocean’ salvia: Fragrant and a butterfly magnet.
  •  ‘Frydek’ Alocasia: Big, emerald green leaves anchor a tropical look.
  •  ‘Kong Red’ coleus: Massive, upright leaves; prefers shade.

Spillers

Trailing over the side of the container, these plants add softness and a little romance.

  •  ‘Neon’ pothos: Chartreuse leaves are like rays of sunshine.
  •  ‘Blanket White’ petunia: Fast grower with cottage charm.
  •  ‘Angelina’ sedum: Foolproof plant with fleshy yellow leaves.
  •  ‘Ivy League Deep Pink’ geranium: Flowers spring through summer.

Fillers

Midsize plants bridge the space between thrillers and spillers.

  •  ‘Aaron’ caladium: White-center leaves look bright and fresh.
  •  ‘Pink Splash’ polka dot plant: Foliage as impactful as any flower.
  •  ‘Mango Tango’ agastache: Peach-color flowers go with everything.
  •  ‘Impreza Violet’ impatiens: Tidy mounds of long-blooming flowers.

5 Things to Remember When Planting a Window Box

Keep in mind a few basic design principles, then unleash your creativity.

Use Repetition in Your Planting

Repetition is a foolproof way to create a cohesive look in a window box. This 15-foot-long box is planted with repeating groups of ivy ball topiary, chartreuse coleus, and white caladium for a sense of flow and order.

Choose a Focal Point

Choosing the centerpiece first means the rest of your plant picks will fall into place. This design started with a lemon cypress topiary. Coleus bridges the colors of the foliage and the brick, and creeping wire vine loosens the design.

Related: How to Install a Window Box

Think About Texture

This arrangement achieves masses of texture by mixing wispy purple fountain grass, croton, and spilling sweet potato vine. The form differences ensure each plant stands out even though the box is tightly packed.

Take Cues from the Landscape

For this garden door container, red-orange copperleaf and variegated sea hibiscus tie into the color of a nearby Japanese maple. It's filled it out with English ivy, which also grows in the backyard, plus Spanish moss.

Stay Consistent

Try choosing a single color palette for plantings all around your house. This window box planting uses green and white, with hints of yellow. If your window box hangs near an outdoor dining table, tuck in fragrant herbs like thyme, oregano, and mint as fillers.

Plant with Confidence

As long as you remember to include a thriller, spiller, and filler that all have the same light requirements, you can assemble a full, colorful window box. Keep garden design elements in mind on a smaller scale, and give your box plenty of water to keep the plants happy all summer long.

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