How to Plant a Window Box

Planted the right way, window boxes offer gardeners endless options for creative designs

Window boxes are a blank slate for you to design and plant in. ellieanneimages/Shutterstock

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. They continue to be a popular landscape element today, and often stand in for front yards at homes that open to the sidewalk.

Although you have 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 assemble a floral creation of your own.

Step by Step

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’s filled with soil and plants, and gets even heavier when watered. We recommend buying a sturdy box made of a hardwood such as redwood or cedar rather than pine (which rots quickly), and then securing the box with a window box bracket.

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.

Pick Your Plants

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.

Don't underestimate how heavy a window box can be—it's filled with soil and plants, and gets even heavier when watered. Roman Kraft/Unsplash

5 Basic Principles to Remember

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. Try planting a 15-foot-long box 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. For example, start with a lemon cypress topiary. Use coleus to bridge the colors of the foliage and the brick, and creeping wire vine to loosen the design.

Think about texture: An arrangement can achieve masses of texture by mixing wispy purple fountain grass, croton, and spilling sweet potato vine. The form differences ensure each plant stands out even if the box is tightly packed.

Take cues from the landscape: For one example of a garden door container, red-orange copperleaf and variegated sea hibiscus tie into the color of a nearby Japanese maple. It’s filled out with English ivy, which also grows in the backyard, plus Spanish moss. If your window box hangs near an outdoor dining table, tuck in fragrant herbs such as thyme, oregano, and mint as fillers.

Stay consistent: Try choosing a single color palette for plantings all around your house. One window box planting might use green and white, with hints of yellow.

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.

Better Homes and Gardens is a magazine and website devoted to ideas and improvement projects for your home and garden, plus recipes and entertaining ideas. Online at BHG.com. Copyright 2021 Meredith Corporation. Distributed by Tribune Content Agency, LLC.