A Korean spice viburnum, or Viburnum carlesii, is a shrub belonging to the Caprifoliaceae family of flowering plants native to southeast Asia. It is valued for the strong spicy aroma of its flowers which can scent an entire yard. For this reason, these garden plants are often placed under windows or along walkways. They can grow to about 6 feet (1.8 m) tall and can spread to a width of 8 feet (2.4 m) or more.
These shrubs have a sprawling vase shape with very open branches that become thicker as they age. Stunning light pink flower clusters appear in early spring, which fade to white in just a few weeks. As the short blooming season ends in early summer, the flowers turn into red or black berries which are very attractive to songbirds and other wildlife. In addition to the colorful berries, the broad, pale green leaves turn reddish or purple in fall, adding to the year round interest of these garden plants.
Korean spice viburnum shrubs are very hardy and will survive temperatures as cold as -20° Fahrenheit (28° Celsius). They prefer to grow in full sun, but they will also tolerate partial shade, and are not picky about soil type. Korean spice viburnum does well in areas with very hot summers and will endure dry weather once they have become established. They benefit from the addition of compost, though care should be taken to avoid overfertilizing this shrub; it may result in too much leafy growth and no flower production.
These deciduous shrubs require regular pruning to keep them manageable and healthy. Viburnums bloom on old wood, so pruning should be done immediately after flowering to give these shrubs time to produce new growth for flowering the following year. Propagating Korean spice viburnum can be done by stem cuttings, which should be taken from soft wood with several leaves on each cut stem. They should be planted in light potting soil and kept in an airtight Ziploc bag until rooted, which usually takes about a month.
Butterflies are attracted to the flowers of the Korean spice viburnum, and many types of butterfly caterpillars feed on the leaves. The Viburnum Leaf Beetle is the only insect pest which causes significant damage to these plants. This beetle is native to Europe, but has spread throughout the eastern U.S. and Canada; it can completely defoliate these shrubs, causing severe die back and even killing them. The beetles can be kept under control by cutting and destroying infested branches although it may become necessary to use a pesticide if the infestation is severe.