It’s pretty much of a cinch to keep window boxes looking lush all summer when there are so many fabulous flowers to choose from. But what happens when the geraniums give up the ghost and the petunias turn puny? There’s no need to throw in the trowel. With a little imagination and a bit of plant know-how you can create eye-catching window boxes that will last through autumn, the holiday season and beyond.

A Fresh Start for fall.

The area of the country where you live determines when window boxes change from things of beauty to eyesores. For some it may be early September, for others, late October. As soon as your summer display starts to look straggly, it’s time to give your pooped out plants the heave-ho. I know it isn’t easy to be ruthless when there’s the promise of a few more blooms. Still, experience has taught me that there is no miraculous recovery in store for a worn out window box.

After you’ve pulled out the summer crop, check to see if the soil has become dry and caked or full of clumps. It is often a good idea to shovel out the contents and start fresh with a new bag of lightweight potting soil. You’ll want to mix in a bit of perlite to help the soil retain water. When the box is clean and ready to be replanted, start by sprinkling in a couple of inches of the mix on the bottom of the box. Once you’ve selected and positioned the plants you’ll keep adding soil until the box is full.

Cool Choices for Autumn Displays.

Chances are, dwarf juniper did not spring to mind when considering plants for a cool weather window box. The fact is there is a wide selection of hardy evergreens with interesting shapes and foliage that are ideal for winter displays. Holly, cypress, spruce, pine, privet, boxwood and ivy are just a few that can brighten a design without demanding a great deal of maintenance. Since many of these plants are slow growers, you may be able rotate them from the window box to another section of the garden, then back to the window box for several years. An occasional trim will keep the little shrubs looking tidy.

One eye-appealing grouping I’ve seen combines boxwood, heathers and ivy. Start with a row of dwarf boxwood along the rear of the planter, then place several pink and white Scotch heathers across the center. To soften the edges, allow trailing ivy to cascade over the front of the box.

Flowering kale (Brassica oleracea acephala "Northern Lights’) and pink or white English ivy make another pleasing combination. For additional splashes of color tuck in a pansy here and there. Perennial herbs are also excellent candidates to incorporate into a cool weather box. Lavender, germander, oregano, mint, lemon balm, chives and thyme are hardy to zones four or five. They look great—and you have the added pleasure of opening your window and harvesting fresh herbs whenever you need them.

The more the merrier.

While visiting France a few years ago I saw some absolutely amazing window boxes. It seemed that every window in every village was alive with color and blooms. I wondered how gardeners there were able to achieve such dramatic displays. In taking with villagers I learned that they incorporate more plants into their window boxes than we generally do. Where we might use five specimens in a planter, they cram in fifteen.

More definitely works better.

Another European beauty secret I discovered is that they fertilize more often than the product label suggests. That practice might be okay for spring and summer boxes, but the result could be deadly for  

plants heading into cooler weather. One dose of a good plant fertilizer should get your autumn box off to a good start. Ask your Growise expert for a recommendation.

The instant window box.