A viburnum hedge creates a dense visual and physical barrier along property lines and between different garden and landscape areas. Types of viburnum shrubs vary widely and can include deciduous, evergreen and semi-evergreen varieties. When making a viburnum hedge, selecting the proper type of shrub, spacing the shrubs correctly at planting time and performing ongoing care and maintenance are important for creating a healthy hedge. This fast growing shrub can produce 1 to 2 feet (about 30 to 60 cm) of new growth a year.
The first consideration when planting a viburnum hedge is to select the type of viburnum to use. Deciduous varieties lose their leaves in winter, leaving the hedge bare for part of the year. Evergreen varieties keep their foliage year-round, while semi-evergreen shrubs always retain some foliage but shed a significant portion of the leaves at one time during the year.
Evergreen varieties can be sheered to create a formal hedge or left to grow as an informal hedge, while deciduous varieties are best grown as informal hedges. A formal hedge is kept neat, in a square or round shape. Hedge clippers are used to shear off the outside growth. An informal hedge is pruned selectively to maintain a natural shape.
It is best to plant a viburnum hedge in a spot that gets full sun or part shade. These shrubs flower in spring and produce the best blooms when planted in full sun. Viburnum shrubs can tolerate brief periods in damp or wet soil, but prefer soil with consistently good drainage.
A new viburnum hedge should be planted in the fall, though spring and early summer planting is also suitable. Evergreen viburnum shrubs intended for formal hedges should be spaced 1 to 1.5 feet (about 30 to 45 cm) apart. Deciduous shrubs and evergreen viburnum planted as informal hedges should be planted 2 to 4 feet (about 60 to 120 cm) apart.
After planting, the shrubs can be pruned to a height of 6 to 8 inches (about 15 to 20 cm) from the ground. This heavy initial pruning encourages the shrubs to produce dense new growth. During the first few years until the hedge has reached the desired height, viburnum shrubs should only be lightly pruned. The best way to encourage dense growth is to prune the branches back periodically during the growing season. Removing 6 inches (about 15 cm) from each branch for every 12 inches (about 30 cm) of new growth keeps the shrubs dense and tidy as they get established.