Window boxes are a popular way of container gardening and there is no reason why their colourful presence should end when summer comes to a close. Using evergreen plants is an easy way to make sure window boxes keep thriving throughout the year. Window boxes can be planted with small evergreens that are either needled or broadleaved. Why not have two sets of boxes -- one specifically for spring and summer flowers, and one for autumn and winter with evergreens.
Dwarf Japanese yew
Japanese yew (Taxus cuspidate) is a conifer that is shade tolerant and therefore a good evergreen candidate for window boxes that do not get enough sun. The tree has dark-green needles with rounded tips and the female plants also have red berries. Though labelled as dwarf, the Japanese yew can grow up to 8 metres in height if left unpruned. Japanese yews can be easily propagated with cuttings or with seed and trained to the desired height for a window box. The plant grows well in moist, fertile soil.
Archtostaphyos uva-ursi is an evergreen shrub that reaches a mature height of about 7.5 to 15 cm with a 1 metre spread. The plant is popularly used as an evergreen ground cover and is well tolerant of sun and shade -- it's a good choice for window boxes given its low height. The plant bears pale-pink flowers in spring and berries in the autumn, which attract birds.
Pieris japonica is an evergreen shrub that is also referred to as Andromeda and lily-of-the-valley. The shrub is not only a good evergreen choice for window boxes for its green foliage, but also for the cascading pink, red and white flowers it bears in the spring. As the evergreen leaves of the pieris mature, they change to a dark green and the flower buds start to develop in late autumn. The plants are commonly used to create shrub borders and as foundation planting. Pieris grows well in partial sun or shade but does not flower as much in shade. They are best planted in rich, well-drained soil.