Window boxes are a tried and true way to refresh your home's exterior, invite some lovely aromas into your home, or boost your culinary supplies (fresh herbs and veggies, yum!). They can instantly add vivid color to your home, or if you live in a small space with no private outdoor access, they are an effective means to incorporate a bit of the outdoors into your daily life. And what's more, they're affordable and easy to care for.
A window box works best if its length falls within a couple of inches of the size of the window. The width and height should be at least 8 inches so that the plants have sufficient root depth and surface area to grow.
There are a number of different styles and materials. Consider what materials might look best with the exterior of your home. Plastic, metal, wood, terracotta? If wood is your option, and you have some simple woodworking skills, it's relatively easy to make your own window boxes. You can find a video tutorial at HGTV or this written tutorial at How Stuff Works. Your window box should have adequate drainage holes. Secure the box firmly to the outside of the window, and be sure to do so with adequate support, since window boxes can be quite heavy.
In order to ensure that your potting soil doesn't escape from the drainage holes, you can line the inside of the box with "crocks," or a layer of broken terracotta or polystyrene packaging. You then have three planting options: to plant directly in the window box, to leave plants in separate pots and fill the space in between them with a lightweight material like moss or bark, or to plant in a liner fitted to the window box. For all of these methods, it's advisable to place a layer of compost in the box, filling it such that the pots will be relatively level with the top of the box.
Then, with the plants still in their pots, arrange the window box, taking into account the factors of height, color, texture, etc., that will determine the finished look of the box. This is the fun part, so let your imagination go! When you're happy with the arrangement, take them out of their pots, place them in the box, and fill around them with soil. Be careful not to pack them too tightly and to leave adequate room for growth.
There's a large range of plants that can thrive in window boxes, so in order to narrow down the choices, first consider your desired use. Is this for visual decoration, for a pleasant scent, for herbs, or even for a small patch of vegetables? If an herb garden, what herbs do you most commonly use? Secondly, consider its prospective location: is it sunny, shady, windy, rainy, sheltered, exposed? And thirdly, think of what aesthetics you want? Do you want one uniform plant, or do you want a variety in your box?
In terms of flowers, some popular choices for annuals are:
• Pansies—Bloom from fall to spring. Need little care, and thrive in most conditions and soils.
• Petunias—Come in a variety of colors and thrive in a number of conditions.
• Nasturtiums—Thrive in rich soils and full sun.
• Sweet Peas—Thrive in rich soils and full sun.
&Lobelia—Good in moisture retentive soils away from extreme heat.
• Impatiens—Good in shade, and come in a range of hues.
• Cyclamen;Good in winter or in shade.
Herbs: Parsley, Chervil, Mint, Tarragon, Chives, Cilantro, Basil, Oregano, Sage, etc. For more on herb window boxes, see this article from Fine Gardening.
Vegetables: Window boxes are conducive to growing lettuces, dwarf carrots, radishes, peppers, and spinach, among other things. For more on how to grow a "mini farm" in a window box, see this article on HGTV.
In order to care for your new plants, one should generally water to keep the soil barely moist. Obviously, this is dependent on the climate conditions and the needs of your plants, but this is usually once a day. Give the plants an occasional boost with liquid fertilizer, and prune when necessary.