Materials needed for all-season window boxes:
• Window box
• Landscape fabric
• Sphagnum moss or sheet moss
For spring, summer, and fall boxes:
• Water-retaining granules
• Potting mix
• Various plant materials
For winter boxes:
• Tree tops such as blue spruce or white pine
• Pine cones
• Floral picks
• Dried sumac with stems at least 8 inches tall
• Berries from holly, bittersweet, winterberry or viburnum shrubs
Preparing and planting your window box
• Choose a deep window box that has good drainage. A box 11 to 12 inches deep provides space for roots to take hold and allows the soil mix to retain moisture longer so you won’t have to water as often—shallow boxes may need to be watered twice a day. For materials, wrought-iron works as long as there are proper drainage holes. Wood maintains temperatures well, plastic is lightweight, and fiberglass is durable and easy to clean. Terra cotta isn’t the best choice for cold-winter climates, as it cracks easily in freezing temps.
• Prepare the inside of your box. Place pieces of sphagnum moss or sheet moss inside the box around the sides and front—this helps keep the potting mix from drying out. Sphagnum moss is less expensive, but sheet moss is an attractive green color. Both are available at nurseries and garden centers.
• Cut a piece of landscape fabric to fit inside the back of the box. This holds the potting mix in the box and saves money because you don’t have to put moss on this side. (See Photo 1)
• Add a good-quality, packaged potting mix to the bottom of spring, summer, or fall window boxes. Sprinkle in some water-retaining granules (as directed on the package) to prevent the soil from drying out quickly. (See Photo 2)
* For winter window box, remove potting mix and water-retaining granules, but leave the moss and landscape fabric in the box. Scoop in sand until it is 2 inches from the top of the box. Sand helps the evergreens retain moisture better than potting mix.
• Water seedlings and potted plants thoroughly; then plant. Space plants closer to each other than recommended to ensure a full box, but not so close that they can’t grow to their full size. (See Photo 3) As you add more potting mix, keep sprinkling in water-retaining granules according to directions. Stop adding mix 1 to 2 inches from the top of the box because water-retaining granules expand when they’re wet.
* For winter window box, you don’t need to water the dried plant material. Twist spruce, balsam, or pine tree tops into the sand until they’re secure. Take a florist pick and wrap the attached wire around the base of a pine cone. Insert pine cones throughout the box so you can see them clearly from the front. Insert bittersweet and berries among pine cones and tree tops; add dried sumac as a final touch.
• Water the entire box. To encourage quicker rooting of transplants, mix a liquid rooting hormone (there are organic varieties available) with water, according to directions, when watering the first time. The moss in your box should be moist but not soggy.
* For winter window box, don’t add the hormone. Water plants until water sits just on top of the sand. Plants will look good for up to five months.
Produced by Kerin Redwanz; Photos by Chap Achen.