Window Box Gardening: Complete Guide to Design, Planting, and Care

Window box gardening brings the joy of container gardening to apartment dwellers and those with limited space. With the right box and plants, you can enjoy pansies and primroses in spring, petunias or fuchsias in summer, chrysanthemums in fall, and greens with berries in winter. English ivy provides trailing green all winter if sheltered from wind.

Choosing and Building the Box

• Size: 3–4 feet long (max 6 feet for hanging; 8 feet for boxes on broad ledges/railings). Minimum depth 8–9 inches, width 10–12 inches.
• Materials: Wood (cedar, redwood, cypress, quality white pine) is most common. Metals conduct heat, risking overheated soil. Plastic, fiberglass, spun glass, and Gardenglas are lightweight and durable.
• Construction: Use 1–1¼ inch thick boards, brass screws (not nails), reinforce corners with angle irons. Drill ½-inch drainage holes every 6–8 inches.
• Finish: Treat interior with non-toxic preservative (e.g., Cuprinol), then apply two coats of paint or stain. Choose colors that complement plants—dark green is traditional, but avoid dark paint with dark flowers or light paint with white flowers.

Installation and Planting

• Secure with bolts or lag screws (treated against rust). Leave 1 inch between box and wall for air circulation.
• If on a solid surface, raise on cleats or bricks to keep drainage holes clear.
• Base layer: 1 inch of broken pots, crushed brick, pebbles, or cinders. Cover with wet burlap, sphagnum moss, leaves, or clinkers to prevent soil loss.
• Use rich soil. Space large plants (geraniums, coleus, fuchsias) 8–10 inches apart; small plants (lobelias, phlox, wax begonias, alyssum, browallia) 6 inches apart. An 8-inch box holds two rows; a 10-inch box holds three.
• Mulch with 1 inch of peat moss. Feed with liquid fertilizer monthly, then every 7–10 days.

Plant Suggestions

Sun: Geraniums (red/pink for light boxes, white for dark), trailing vinca, ivy, dwarf marigolds, lobelias, verbenas, sweet alyssum, balcony petunias.
Shade: Coleus (especially Trailing Queen), English ivy, creeping jenny, Kenilworth ivy, creeping fig, German ivy, variegated ground covers, wandering Jew, zebrina, achimenes, chlorophytum, star of Bethlehem, Italian bellflower, strawberry begonia.

Be creative with color and texture—window box gardening will quickly become a favorite hobby.