Window Boxes for Plants

Mom's birthday is on the horizon, and I'm thinking window boxes. For as long as I can remember, she's always kept a vibrant perennial garden full of snapdragons, salvia, and alyssum at the foot of lilac and rose of Sharon shrubs. But years of bending to weed and cultivate have weighed on her knees, and Mom's garden has become more of a shrub garden. I want to perk up her summer days with a colorful window box, a box whose height will spare her worn knees.

"Window boxes usually are full of color and textures, so you don't want a lot of empty spaces in the box," explained Pandora Flores, assistant manager at Armstrong Garden Center. "Annual flowers have a lot of color but they don't last a long time, so you need to replenish them every two to three months. We recommend putting a mix of annuals and perennials. The perennials last year-round, so you just replenish the annuals. Ivy geraniums are a good plant because they cascade down and flower just about year-round. Vegetables or herbs can be incorporated in the planter. Or you can do succulents or cactus, which last a lot longer than the annuals.

"People often go for the plastic window boxes because they're less expensive," Flores continued (plastic terra-cotta-colored boxes cost $9.99 for the 30-inch planter). "We sell wooden window boxes also [$33.99 for the 36-inch-long box].

"The main focus is drainage, good drainage in the bottom of whatever container that you choose. Put holes in the bottom, anywhere from four to six inches apart, so the water doesn't stay in there when you water it. You can put gravel [or broken clay pieces] on the bottom of the planter, which helps keep the water away from the root systems so they don't drown.

"You need to water window boxes more frequently than you would a garden," added Flores. "Anything in containers, especially shallow containers, which window boxes tend to be, you need to water more frequently. Incorporate a slow-release type of fertilizer into the soil when you are planting, so you do not have to keep fertilizing. Those fertilizers last anywhere from four to nine months.

"For the wire-style boxes," continued Flores, "you need coconut fiber to contain the soil in the box. Get a high-quality coconut fiber so that the fiber will retain moisture well. Sometimes lower-quality fibers dry out really fast."

Mia McCarville, owner of Cedros Gardens, stocks a window box called a Hayrack. "It is a long, black, wrought-iron window basket," she explained, "with the molded coconut liner, made by Tom Chambers in England. It has a real traditional English garden look. The Hayrack starts at $35 for a 28-inch box, and they go up to $96 for the four-feet-long box." McCarville suggested planting strawberries in your window box. "That would be very cute," she added.

Wally Jarns, buyer for Evergreen Nursery, suggested lobelia as an edging. "Lobelia is a good edging for a window box; it hangs over the side. Annuals like alyssum, marigold, petunias, whatever is in season, you can use as your middle plant." Jarns cautioned against using perennials in the planter. "Usually the window box is not deep enough for perennials. Perennials need more root area because they are going to grow larger and longer."

"The main thing with a window box," said Stephanie Scanga, assistant manager at Smith & Hawken, "is that it is hard to keep a window box damp, because it is surrounded by air. Ours are really nice because we carry a fiberglass shell [which goes inside the window box], so the soil doesn't dry out from the side and the bottom. It keeps the plants much more like they are in the ground so the box doesn't put as much stress on the plants. The fiberglass shell is also element stable, meaning it won't erode with the weather."

Scanga continued with design options. "I always say, look around and see what grows best in other people's window boxes. Generally it is plants that will take a lot of sun, like geraniums, ivy, or angel vine. The other thing to remember with window boxes is that when you install them onto your house, you want to match the hardware to your house, not the window box." Scanga pointed out a wall of boxes. I saw a few favorites. The faux terra-cotta resin box, with relief fruit and leaves on it ($69 for the 36-inch box) was a bargain for its authentic look. The Soho Window Box ($225 for the 48-inch box) reminded me of penthouses in Manhattan, with its circular art deco design on the black steel. And the Canterborough Window Box caught my eye. The label on the black steel read "inspired by an antique garden gate." The price: $195 for the 48-inch box.

Restoration Hardware offered a snazzy green-blue metal box called the Zinc Tabletop Windowbox for $39 for the 24-inch box.

Walter Andersen's Nursery was selling 24-inch redwood boxes for $24 and 24-inch white-, green-, and terra-cotta-colored plastic boxes for $16.

1. Ivy geranium

2. Flower box from Restoration Hardware

3. Lobelia