There are many choices of plants for window boxes--some are grown for their scents while others are used in the kitchen and bath. Knowing the growth habits of different plants goes a long way in making an informed decision on what plants are best for your needs. Creating layers of different growth types produces a more visually stunning planting than single species plantings. There are many plants that offer year round appeal, with some offering evergreen foliage to those that even bloom in winter.
Violets are a good choice for window boxes as they are undemanding in their care requirements and offer their grower masses of beautiful blooms. Ranging in colours from white, yellow, blue and purple, they make customising a planting less of a chore than plants that bloom in one shade. Choose hardy violets that are bushy with dark green foliage and a tight growth habit. Avoid leggy, yellowing plants, as they are unhealthy.
Miniature and Dwarf Conifers
If kept trimmed and mulched with their roots protected from freezing weather, conifers make interesting additions to a window box arrangement. Choose plants that have dense and small needles that are attached firmly to their limbs. An underplanting of a ground hugging plant will help the conifers to stand out.
Creeping Jenny is a low-growing perennial that, when planted in containers and kept well watered, will spill over the edges of the pot to create a waterfall of green or golden leaves. They are easy to care for and spread fast to fill in bare areas.
Like creeping Jenny, creeping Charlie is a low-growing perennial with a spreading habit. The leaves are as miniature versions of ivy and the plants produce dainty dark violet blossoms. When healthy, creeping Charlie has deep green leaves and is smothered in purple blossoms. It will also spill over the edge of pots.
Mint is especially suited for growing in containers. It is tough and hard to kill as well as fast to spread and fill in bare areas (which is why most people keep them in containers). Mint responds very well to constant trimming to keep it in shape. If the plants have been grown without the use of pesticides or other dangerous chemicals, cuttings make a nice addition to tea and salads as well as natural breath fresheners and rodent repellents.
Bittersweet vines can be kept trimmed to reasonable sizes and make excellent choices for framing windows. Their leaves offer winter interest turning from dark green to orange and golden yellow. Mature female vines (if planted with a male) will produce copious amounts of brilliant red-orange berries. Birds appreciate the berries as much needed winter food.