Tired window boxes can be revived for fall
If your window boxes are looking summer worn, take advantage of the opportunity to give them a refreshing fall makeover. Whether your window boxes need a complete overhaul or just some pruning and selective replanting, their makeover should keep them attractive well past Halloween.
Begin by removing any plants that are beyond saving or those that will wilt with the first sign of frost. Annuals, like pentas and impatiens, that are past their prime are ready for the compost bin. Coleus and sweet potato vine may be standouts in summer designs, but they collapse during the first frosty night. Off to the compost bin they go, too.
Use a garden knife to cut around plants to be removed and pull them gently so damage to roots of desirable neighbors is minimal.
If a plant has grown too large but its form can be saved with pruning, prune away. Examples of these include petunias, snapdragons and verbena. Trailing plants, like ivies and creeping Jenny, can also cut back to maintain correct proportion. A simple nip or tuck may be all that annuals need that perform well in cool weather, too. Alyssum responds well to pruning.
Garden centers offer fresh crops of annuals that perform beautifully in cool weather. Pansies and mums are the most expected. Snapdragons, dianthus, marigolds, petunias and many herbs, like parsley and thyme, are just a few of other plants commonly available.
Ornamental cabbage and kale offer interesting foliage texture in window boxes. Their thick, rounded or frilly leaves are available with tones of pink, red or white. The color intensifies as temperatures drop, and their excellent cold tolerance keeps them looking beautiful until Thanksgiving (and sometimes Christmas).
Consider using perennials, too. Often on sale at garden centers in the fall, perennials that are lovely in fall containers include sedums, dwarf asters and small grasses. The fleshy foliage of sedums may be gray-green, blue-green, green or purple. Their flowers bloom in shades of pink. Some varieties are mounding; some soften the edges of window boxes. Dwarf asters contribute masses of small blue, lavender, pink or white flowers. Small grasses or sedges offer fine texture, contrasting with the bold presence of ornamental cabbage or mums.
The burgundy foliage of purple fountain grass is gorgeous when mixed with other autumnal hues. If purple fountain grasses were in your summer window boxes, leave them. Their burgundy leaves will turn tawny brown as temperatures fall but remain upright until heavy snow falls.
Look around the garden for dried seedpods that can be tucked into unique fall container designs. Coneflowers, black-eyed Susan, sunflowers, allium, poppies and yarrow are just some of the options. Cut some branches from a bittersweet vine and let it trail over the edge or wind its way through other plants in the window box.
Replanted window boxes take less care in fall. Cooler temperatures mean less watering and deadheading is required. Little, if any, fertilizer is needed. If a plant disappoints, simply remove it, and replace it with a gourd or mini pumpkin.
As Halloween draws closer, add some bundled corn tassels or the tops of broom corn, gourds and baby pumpkins to create a harvest look. Add some straw around the bases of plants.
Don't give up on beautiful window boxes just because summer is behind us. Some autumn alterations are all that is needed to keep them attractive into November.
• Diana Stoll is a horticulturist, garden writer and speaker. She blogs at gardenwithdiana.com.