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Spring in bloom
Charleston’s historic homes are adorned with window boxes bursting with color each spring. This dramatic black planter is anchored by ornamental kale on each end, gets a dramatic backdrop from the red-and-green foliage of Bloody Sorrel/Red Dock and pink-flowering flamingo plant, and fills in with purple Million Bells trailing petunias, dark pink Gerbera daisies and the succulent trailing sedum.
Photo by Amy L. Dabbs
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Box mix
A mix of trailing and upright plants and a variety of colors and textures make for an attractive window box. African iris and summer snapdragons add height in this hayrack, while wave petunias provide a pop of darker purple, and variegated ivy and white sweet alyssum drape gracefully over the edges.
Photo by Amy L. Dabbs
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Gap filler
The billowing clouds of tiny white flowers and emerald-green foliage in Diamond Frost Euphorbia look great in partial- to full-sun window box combinations, especially tucked between larger plants.
Photo by Amy L. Dabbs
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Sun or shade
With its velvety texture and colorful foliage, Lime Shrimp Coleus thrives in sunny or shady conditions.
Photo by Amy L. Dabbs
Every spring, thousands of visitors tour the Holy City to snag glimpses and photos of historic homes festooned with window boxes, all bursting with colorful flowers and foliage. But why wait for a trip to Charleston when you can create your own showy window boxes at home?
Knowing a few tricks will help you achieve that signature look.
Step one is choosing the right box. Consider the style of your home. Classic, wrought-iron boxes go well with traditional brick homes. White vinyl or painted-wood boxes contrast well with darker siding. Boxes with decorative trim add charm to cottage or Victorian-style homes.
Your box also sets the backdrop for the plants you showcase. Metal hayracks lined with coco-fiber mats or wooden boxes painted dark green provide a neutral setting for bold plant combinations. For a fun, modern twist, choose bright colors on sleek window boxes.
Local garden centers, home-decor stores and home-improvement centers sell premade boxes in assorted styles. DIY types can find countless plans online for building custom window boxes.
You’ll need boxes at least 6 inches deep to accommodate expanding roots and enough soil so plants won’t dry out quickly. For the height, measure your windows first, and choose boxes 20 to 25 percent as high as your windows. Boxes should be nearly as wide as your windows, or they tend to look skimpy.
Good drainage is critical. If your window box lacks drainage holes, drill ½-inch holes every 6 to 8 inches along the bottom. Line it with screen cloth to hold soil in place. Fill to within half an inch of the top with a well-drained, lightweight, soilless growing mix made for outdoor plants. Don’t skimp on this; your plants will need all the moisture their roots can reach in the heat of Southern summers. If the growing medium does not contain a slow-release fertilizer, mix it in prior to planting, following label directions.
Since window boxes are seasonal, feel free to ignore plant-spacing recommendations; instead, plant tightly to achieve a full look. Be sure you’re combining plants with similar water and light requirements, but otherwise, use your creativity to mix bromeliads, orchids, decorative foliage, edible herbs, ornamental vegetables or whatever you like.
If you want to avoid blocking your view from indoors, plant an airy, low-growing mix. Butterfly flower, so called because its delicate flowers hover over the mounding foliage, is a nonstop bloomer that thrives in full sun. Compact varieties grow only 12–18 inches high. Diamond Frost Euphorbia softens edges and fills in gaps between larger plants.
For bold color and texture in smaller packages, try compact favorites like sweet potato vine and coleus. Compact Margie potato vine provides bright, chartreuse color in full sun to partial shade but won’t hog all the space and water. Yellowfin Tuna and Lime Shrimp, new varieties of sun coleus, thrive in sun or shade and add velvety texture.
All window boxes should showcase trailing plants that gracefully sweep down. Million Bells, or trailing petunia, is a workhorse, blooming from spring until heavy frost in a wide array of colors. Silvery foliage plants, such as Silver Falls and Silver Mist licorice plant (Dichondra argentea), thrive in full sun, adding a cool, metallic sheen in summer.
Get height and bold color with heat-tolerant Savannah series geraniums, or choose perennial African irises for tall, grass-like foliage and tropical white flowers.
Check the soil’s moisture level daily. If the soil feels dry 1–2 inches under the surface, give plants a good soaking beneath the foliage, until water runs out the drainage holes. Feed with a water-soluble fertilizer labeled for blooming plants every other week throughout the growing season.
Count on regularly refreshing your window boxes to keep them tidy. If a plant begins to look tired, simply remove and replace it or let neighboring plants take over. Nip back leggy plants, deadhead spent blooms and rein in unruly foliage.
AMY L. DABBS is an area horticulture agent for Clemson Extension based in Charleston County. Contact her at adabbs@clemson.edu.