Korean spice viburnum (Viburnum carlesii), is a deciduous flowering shrub with wonderfully aromatic flowers. It grows in USDA plant hardiness zones 4 through 7 and makes a great specimen plant for spring blossoms. The flowers start as pink buds and change to white blooms with a hint of the early pink color. The white flower clusters are nicely rounded and very fragrant.
Be careful not to confuse this plant with spicebush (Lindera benzoin) or California allspice or California spicebush (Calycanthus occidentalis). Viburnum carlesii is in the Moschatel family of plants, which also includes elderberry (Sambucus spp.).
As with nearly all deciduous shrubs, spring is the best time to plant Korean spice viburnum, as this gives the plant plenty of time to develop a good root system before winter. Like most viburnum shrubs, this is a relatively slow grower, adding 1 to 2 feet per year until it reaches its mature size of about 6 feet. Some cultivars are shorter plants, but these are even slower growing, still requiring at least three years to reach their mature size.
|Botanical Name||Viburnum carlesii|
|Common Name||Korean spicebush|
|Plant Type||Deciduous flowering shrub|
|Mature Size||6 feet tall and wide|
|Sun Exposure||Full sun to part shade|
|Soil Type||Moist, well-drained|
|Soil pH||5.6 to 6.6 (acidic to neutral)|
|Hardiness Zones||4 to 7 (USDA)|
|Native Area||Korea, Japan|
How to Grow Korean Spice Viburnum
Plant Korean spice viburnum in average well-drained soil in almost any exposure conditions except dense shade. It is one of the more trouble-free of all shrubs.
The very fragrant flowers on the Korean spice bush are replaced by red berries in summer, provided a compatible cross-pollinator is present. In other words, these bushes are not self-pollinating, they need a partner.
In autumn, the berries mature to a dark, almost black color. But if you are looking forward to fall color, count more on the foliage rather than on the berries. The fall leaves start out reddish but then turn to a purplish color.
If you still wish to try for berries, you'll be faced with the cross-pollination challenge, which is twofold:
- The pollinator plant cannot be of the same cultivar. So, for example, you cannot pollinate an 'Aurora' with another 'Aurora.' Instead, you would have to pair your 'Aurora' with another viburnum from the same species (a hybrid bred from the same species will also work).
- The pollinator plant must also come into bloom at the same time as the plant from which you are trying to grow berries. Because plants bloom at different times in different areas, ask local nurseries or extension service to recommend a suitable pollinator.
One possibility is to pair a V. carlesii with a V. x burkwoodii 'Mohawk', because the latter is a hybrid cultivar, with one of the parents being V. carlesii. But before you buy, inquire at the garden center if the two plants come into bloom at the same time in your area. Better yet, if you will be shopping for the two at the same time, buy them only if both are blooming.
Plant this shrub in full sun to part shade.
These bushes grow best in the moist but well-drained ground with slightly acidic a soil pH. They do not do well in very wet soil.
Maintain evenly moist soil with regular watering. Weekly watering is typical in many areas, but drier climates or seasons may necessitate more frequent watering. This plant is relatively drought-resistant once established but will perform best if it receives a deep weekly watering during dry spells
Temperature and Humidity
Viburnums are generally tolerant of high heat but do best with some shade during the hottest periods of summer. They prefer humid climates, but will tolerate dry conditions.
Feed the plant in spring with a slow-release tree and shrub fertilizer to support overall health and promote future blooms. Don't feed late in summer because this can force new growth that can be damaged by fall frost.
Korean spice viburnum buds form on the prior season's growth. Therefore, if you wish to prune the plants in order to shape them and/or restrict their size, do your pruning just after they have finished flowering. Simply cut the branch tips to promote further branching and a bushier look. Also, remove any dead branches and those that rub against each other.
Common Pests/ Diseases
One problem you can experience in caring for this plant is leaf curl at the tips of branches. The culprit will most likely be aphids. If you can manage to catch them in action, spray them with organic neem oil. But aphids can come and go very quickly, leaving a damaged leaf behind. Luckily, if restricted to just a relatively small portion of the entire plant, leaf curl does no long-term harm. It is problematic only on an aesthetic level, marring the appearance of the foliage during summer and fall. Prune off the affected branch tips and dispose of them properly, and the plant will be none the worse for it.
Varieties of Korean Spice Viburnum
Several varieties of Korean spice viburnum are available, some of which are cultivars, others that are crosses between V.carlesiii and other species:
- 'Aurora' is a slower-growing rounded shrub that generally stays around 4 to 5 feet in height.
- ‘Compactum’ is a smaller variety of Korean spice viburnum that grows 2 1/2 to 4 feet tall and wide with flowers colored the same as the pure species, white.
- 'Spice Bouquet' is a 4 to 6-foot shrub with soft pink flowers that fade to white.
- 'Spice Island' is 3 to 5 feet tall with white flowers, and dark green leaves with good red fall color.
- 'Sugar N' Spice' is 4 to 5 feet high with dark green leaves that turn maroon-red in fall.
- Viburnum × carlcephalum is a cross between V. carlesii and V. macrocephalum var. keteleeri. It has large snow-ball-like flowers, and is hardy in zones 6 to 8. It grows 6 to 10 feet tall.
- Viburnum x burkwoodii (Burkwood vibernum) is a cross between V. utile and V. carlesii. It is a broad, dense shrub reaching 8 to 10 feet, with flat-topped white flowers blooming in April.
The single most outstanding feature of Korean spice viburnum shrubs is their aromatic quality. Another benefit is that these shrubs are among the first flowering shrubs to bloom in early spring, satisfying our craving to see springtime color as soon as possible once winter ends. Honorable mention goes to the color of their fall foliage. In fact, they are undoubtedly one of the best shrubs for fall color.
Due to their exceptional fragrance, you might include these shrubs in your entryway landscaping or as foundation shrubs to fully appreciate their aroma. They also attract butterflies and are a food source for Spring Azure Blue butterfly caterpillars. Wild birds feed on the berries (if present), and the shrub is generally considered to be rabbit-proof.