During dormant months, window boxes can showcase the best of the season. Deborah Silver, of Detroit Garden Works in Sylvan Lake, and Sylvia Jamieson and Stacy Feldman, of Four Seasons Garden Center in Oak Park, offer the following tips for cold-weather sills.
• Selectively remove some existing summer-color plants and replace them with new specimens for fall color (hakonechloa grasses, bittersweet, and Echinacea “tomato soup,” for example). Fill with pumpkins, gourds, and grapevine.
• Today’s trend is to use more shrubs in dwarf and compact varieties, ones that will transition through the year. (Consider a small or low-growing evergreen to anchor the design. Add evergreen ground covers, such as Boston ivy.)
• Add cold-tolerant plants in fall colors to extend the planters through Thanksgiving. Kale, pansies, chrysanthemum, and zinnia “Profusion Orange” perform well.
• Use cuttings of yard plants with strong fall colors (rhododendron PJM, hydrangeas, dwarf fothergilla, or burning bush) and place them among the existing plants and water well to keep them fresh.
• For winter, use evergreens of all kinds (holly and cedar, for instance, either planted or as boughs pruned from the yard) as the foundation. Stuff the box with cuttings, pine cones, and red berries. Add sparkle with lighting, foam snowballs, and colorful ribbon.
— Four Seasons Garden Center, Oak Park; 248-543-4400, fourseasonsgardencenter.com.
• Dwarf evergreen shrubs look great, but don’t count on them to survive the winter. Take them out of your fall boxes before winter, and plant them in the ground until the following year.
• Fall is all about the harvest. Include pumpkins, squash, and cabbages. (Make sure they’re intact; a pumpkin with holes will rot more quickly.)
• Shop local farmers markets and garden centers for interesting autumn material. Check your yard for twigs, branches, and grasses. Dried grapevines and bittersweet vines make great trailers.
• Fake stems have come a long way; they can fool the most-discerning eye. Faux versions provide height where you need it. (Be sure they’re intended for outdoor use.)
• When composing, start in the center of the box and work to the edges. Alternate textures and colors for maximum impact from the street. Monochromatic schemes are great viewed up close. Use ample material; the best boxes have a bountiful look.
• Remove the top 4-6 inches of soil from the box before the ground freezes and fill that space with dry floral foam. The foam should be 4-6 inches higher than the rim of the box, which allows you to stuff cut greens in sideways for a more natural look. Fill boxes to mimic the look of a natural shrub.
• Red- and yellow-twig dogwood, kiwi vine, curly willow, and black willow are among the many twigs that provide great winter color. Preserved spiral eucalyptus holds up well. Fake berry stems add more color.
• Lighting the branches in a box, or the ground level of a box, adds the one element we miss so much in Michigan winters: light.
— Detroit Garden Works, Sylvan Lake; 248-335-8089, detroitgardenworks.com.