Siebold’s Arrowwood (Viburnum sieboldii) is a broadleaf deciduous tree with green foliage and white flowers in spring followed by red and black fruit. Attractive to birds, bees, butterflies and hummingbirds. To grow well, it prefers sun – mostly shade and regular water. Grows happily in well-drained and rich soil.
I. Appearance and Characteristics
Viburnum sieboldii, or Siebold’s viburnum, is a plant in the muskroot family, Adoxaceae.
The tree height is 2 to 5 m, but the larger one reaches 7 m in height. The bark of the trunk is brown gray and smooth. The young branches are green with white hairs that grow from green to brownish gray.
The leaves are opposite to each other, the petiole is 5 to 20 mm long, has some hair, has a wide groove on the top surface, and rarely has a bamboo leaf. The leaf blades are 5 to 15 cm long, 2 to 9 cm wide, the shape is elliptical to the shape of a fallen egg. There are sharp or coarse saw blades at the edges, but no saw blades near the base.
At the end of the branch, a pyramid-shaped scattered inflorescence with a length of 4 to 7 cm and a diameter of 6 to 14 cm is attached, and many white flowers are densely attached. Inflorescence branches are usually opposite, and there is usually hair along with the inflorescence axis.
The fruit is an oval drupe that is 8 to 10 mm in length, initially red and then black when fully ripened. The nucleus that contains one seed is an oval that is 7 to 8 mm long and about 2.5 mm thick, with one deep groove running vertically on the ventral side of the nucleus.
II. How to Grow and Care
Siebold’s viburnum is a low-maintenance shrub commonly appreciated for its resilience and adaptability. It prefers well-draining soil and requires regular watering, especially during dry periods, to promote healthy growth. One special care point for siebold’s viburnum is to offer it partial to full sun exposure to encourage optimal flowering and foliage density. Another is to prune it occasionally to maintain its shape and remove any dead or diseased branches, typically after the blooming season.
Sunlight
Siebold’s viburnum in cold environments loves to grow in full sun on slopes and edging rocks in its natural habitat. Varieties adaptable to warmer climates grow well in full sun to medium shade; long exposure to strong light should be avoided. They can be shaded by buildings or big trees. A certain amount of scattered light is needed in the flowering phase to ensure enhanced and continuous flowering in warmer climates, but overall, plants in this genus perform well receiving 5-6 hours of continuous sunlight in a day.
Temperature
Siebold’s viburnum in cold environments loves to grow in full sun on slopes and edging rocks in its natural habitat. Varieties adaptable to warmer climates grow well in full sun to medium shade; long exposure to strong light should be avoided. They can be shaded by buildings or big trees. A certain amount of scattered light is needed in the flowering phase to ensure enhanced and continuous flowering in warmer climates, but overall, plants in this genus perform well receiving 5-6 hours of continuous sunlight in a day.
Watering
Originating from regions with variable moisture, siebold’s viburnum has adapted to a moderate water regime, thriving in conditions that mimic its natural habitat’s intermittent rainfall. This species is known for its resilience and can tolerate short periods of dryness, requiring watering once every 1-2 weeks. In terms of its indoor or outdoor growth preference, siebold’s viburnum is predominantly an outdoor plant, where it benefits from the natural precipitation cycle. Its deciduous nature means it will require less water during the dormancy period in colder climates, aligning its hydration needs with seasonal changes.
Soil
Siebold’s viburnum likes fertile, soft, slightly acidic soil with good drainage. It likes moist soil but does not grow well in waterlogged soils. It can grow in moderately fertile, fully drained soils that keep minimum moisture, but cannot withstand poor soil. The optimum soil pH range is 5.5-6.6. It can tolerate acidic media and drought with good air circulation in the root zone, which is made possible by the addition of peat moss or coco coir to the media. The best potting soil would be to mix 1 part of fully decomposed organic matter into 2 parts of garden soil.
Fertilizing
Applying organic fertilizer in a planned and reasonable way can improve soil structure, increase soil organic matter content, and increase soil fertility. Fertilization is indispensable for growth, and fertile soil promotes the overall growth of the plants. When transplanting, apply an adequate amount of basal fertilizer, and apply fertilizer every 2 weeks during the flourishing growth stage. Fertilizer should be applied when the weather is clear and the soil is dry.
To ensure normal growth, fertilization should be carried out before the dormant period or after the leaves are preparing to fall, and before the soil freezes. Don’t fertilize the soft cuttings until they start sprouting. For transplants, fertilizer rich in nitrogen is necessary to initiate vegetative growth. In the later flowering stages, it can be replaced with high phosphorus fertilizer.
Planting Instructions
The best time for transplanting is in late spring or early summer. It is best to plant them all on the same day. Take care that roots aren’t exposed to direct light and are buried deep into the planting pit.
Before planting, you need to know the height of a fully mature plant for the variety that you are growing. Generally, the role of thumb is to divide the height of the plant by 2 to determine space. For example, if the selected variety is predicted to grow 4 m tall at full maturity, space the plants 2 m apart. Dig a pit measuring 30 cm deep and 30 cm wide.
Pruning
Light pruning to remove dead or dried branches or injured parts of the plant can be done at any time of the year. Siebold’s viburnum doesn’t need severe pruning; how much depends on the type of variety and purpose of growing.
Pruning to shape and beautify can be done in the late winter or early spring. When growing for borders and hedges, cut only 1/3 of the branches if they are severely intermingled. In other cases, pruning can be initiated right after flowering but before the setting of fruit. To avoid frost damage, don’t prune during frost or severe cold.
Propagation
Native to East Asia, siebold’s viburnum is best propagated through stem cuttings. Carefully select healthy, semi-hardwood sections and make clean cuts. For optimal rooting, treat the base with a rooting hormone and position them in well-draining, moist soil under indirect light. Maintain consistent moisture while siebold’s viburnum establishes roots. Regular inspection for pests and disease helps ensure successful propagation, fostering new, vigorous growth over time.
Transplanting
Optimum times for transplanting siebold’s viburnum are when nature awakens in late spring or when it begins to rest in late fall, embracing gentle temperatures ideal for root establishment. Choose a sun-dappled spot with well-draining soil, and ensure ample space for growth.
