Sprucing up a facade is just the start of the window box's talents. Its potted plantings also bring garden scenes up close and invite flowery perfumes indoors. And because window boxes are so prominently placed—and generally on public view—they claim more attention than patio pots without requiring any additional effort or expense. They're amazingly versatile, especially if you push past a mere gathering of geraniums, as pretty as those can be, for a layered mix with nuance and dimension.
Like any garden planting, a window box comes with its own set of design considerations. Its close tie to the house is one. Study your home's exterior to see which windows need dressing up and what cues the architecture provides. Traditional houses, especially, welcome window-box plantings, which play up elements such as shutters and handsome trim.
But look from the inside out, too. Consider which rooms you use often enough to warrant flower-edged views, and give thought to plant size and placement, as these window plantings can also be a chance to add privacy.
Dwarf conifers, for instance, can block unwanted views year-round, while grasses are perfect for light screening. For boxes below casement windows, tuck in low growers that won't mind being brushed over; for lofty second-story boxes, show off graceful spillers that cascade dramatically.
Shown: This box has it all. Wispy gaura improves the view indoors and out; golden creeping Jenny adds cascades of foliage; and salvia, 'Phantom' petunias, and 'Diamond Frost' euphorbia fill in the lush display.
Window Planter Box Ideas
A Balanced Approach
As with ground-level beds, light conditions will determine what you can grow. Full sun accommodates blooming annuals, while shade best suits foliage plants, like coleus and caladium. To properly show off these displays, select a box that's the same width as the window. Use sturdy brackets to attach the box to your house, and invest in a high-quality potting mix.
Arrange plants on top of the soil until you're happy with how the design looks from inside and out. Then ease them out of the nursery pots and settle them in. Some crowding is fine, as long as you keep pruners handy to rein in rampant growers. You can also just drop potted plants directly into boxes and surround them with soil. This makes swapping out poor performers and popping in seasonal selections a snap.
Shown: The silver leaves of this euphorbia tone down a boisterous mix of striped petunias, purple lobelia, and hot-pink nicotiana.
Soil, Fertilizer and Planting Strategies for Year-Round Installment
With a little effort, you can keep box displays going strong all year. Regularly check the soil, daily in hot weather, and water thoroughly when it feels dry a half inch down. Since nutrients wash out quickly from containers, fertilizer is a must. Good options include fish emulsion or liquid kelp, diluted to half strength and applied every two weeks.
Switch out cool-weather plants—pansies and cyclamen, say—for heat-lovers, like marigolds, as summer arrives. And as temperatures drop, try sneaking in edibles, like lettuce, for fall and a row of dwarf conifers for winter color.
Read on for more planting strategies to embellish a window-box planting, one that can last as long as you wish and will never stop pleasing.
Shown: A cheery combo of lantanas, impatiens, geraniums, petunias, and sweet alyssum spills over a deep box that spans three windows.
Window Flower Boxes: Use Spillers to Add Drama
Trailing plants balance upright growers while warming up walls with their soft textures. Good picks are plants with naturally vining or spreading habits.
Shown: A fringe of white-flowering bacopa beneath scarlet geraniums, double petunias, and pale-yellow calibrachoa calls attention to these windows with lattice muntins.
Pop and Drop: Ivy and Vine
Trailing variegated ivy and purple sweet-potato vine ground an exuberant display of flowering society garlic, petunias, angelonia, pink nicotiana, and white impatiens.
The stems of bacopa, dichondra, and parrot's beak drape down as geranium, lobelia, 'Diamond Frost' euphorbia, and calibrachoa add welcome color.
Sweet Potato Vine: Front and Center
A lime-hued tumble of sweet-potato vine is the focus of this ethereal mix of lobelia, bacopa, 'Diamond Frost' euphorbia, calibrachoa, and licorice plant.
Pops of Contrasting Flowers
Ivy geranium drapes over the box's edge, while the cool hues of purple verbena and wispy gaura enliven the window's crisp white trim and shutters and contrast with the yellow-flowering hedge below.
Simple Display of Flowers
A trimming of white-flowering bacopa adds textural interest to a layered mass of familiar pink and white impatiens.
A tumble of chartreuse sweet-potato vine jazzes up an otherwise subdued planting of white petunias, soft purple angelonia, violet lobelia, and pale-yellow lantana.
Evergreens for Structure
Sized right and easy to shape with clippers, dwarf evergreens anchor fleeting annuals. Choose the hardiest varieties you can find to increase chances of winter survival.
When yellow-green dwarf Hinoki cypress meets 'Blue Star' juniper, the contrast in hues plays up their soft textures, while a tuft of violas adds a punch of color.
Boxwood balls ride a wave of pink petunias, sweet alyssum, and geraniums. In Zones 6 and above, a potted boxwood can survive year-round.
A dwarf Alberta spruce, which gives privacy to the room behind it, is offset by dwarf Hinoki cypress and a ruffle of pink petunias.
Foliage for Steady Color
As flowering annuals go in and out of bloom, foliage plants maintain their eye-catching impact. Some, like grasses that plume in fall, change with the seasons, while others, like coleus, need flower buds pinched to keep leaves robust.
Greens and cream plants
A mass planting of caladium, rex begonia, dichondra, coleus, and plectranthus weaves a tapestry of variegated leaves in varying sizes and shapes.
The autumnal plumes of purple fountain grass provide a vertical foil for fancy-leaf geraniums, purple angelonia, and cascades of stonecrop.
Blue and White Flowers
The flower-like foliage of a silvery euphorbia brings sophistication to this cheerful jumble of tiarellas and pastel violas.
Pollinators flock to variegated Jacob's ladder. Its foliage is a showstopper amid sweet alyssum, penstemon, bacopa, lobelia, and 'Apple Blossom' nicotiana.
This stonecrop's rose-tinged leaves and the purple and pink blooms of phlox and verbena echo the hues of the in-ground hydrangea, tying the box to the rest of the garden.
A ribbon of chartreuse sweet-potato vine adds dimension to a robust planting of white bacopa, purple fan flower, magenta angelonia, and petunias.