Chinese Snowball Viburnum (Viburnum macrocephalum)

Chinese Snowball Tree, Chinese Snowball Viburnum

Chinese snowball is the plant for a savvy spring gardener. Statuesque in scale, one shrub is all you need to make a statement. Laden with hydrangea-like blooms, a single specimen can add oomph to the border or be trained into a small accent tree, blending beautifully into any yard.

I. Appearance and Characteristics 

Viburnum macrocephalum (Chinese: 繡球莢蒾 “hydrangea viburnum”, or 木繡球 “tree hydrangea”), common name Chinese snowball, is a species of flowering plant in the family Adoxaceae (formerly Caprifoliaceae), native to mainland China. Its fertile form, Viburnum macrocephalum f. keteleeri (Chinese: 瓊花, qiong hua, “white jade flower”), is of great cultural significance in China.

Chinese Snowball Viburnum, Viburnum macrocephalum, is a beautiful shrub with hydrangea-like flowers to include in your landscape. With a rounded form and a semi-evergreen nature, this shrub blooms in the late spring with large, 8-inch white flowers. They start out with a light green tint, but develop into elegant, snowball-sized flowers. During the other seasons, this shrub has simple green leaves that make it a great backdrop for other plants in the landscape. These are large shrubs that can grow up to 12 feet tall and wide.

The Chinese Snowball Viburnum is native to China, but does excellent in growing zones 6 to 9. These shrubs are great in mass plantings to create backgrounds, borders or hedges. The dark leaves are semi-evergreen in southern regions. Which means that some of the leaves fall off, but some of the foliage is there all year. The flowers are the size of softballs, and the bushes are often covered in the flowers from April through May (depending on where you live).

These plants do not produce seeds which means they are a non-invasive plant that is botanically sterile. This also means the plants do not produce fruit like other viburnums will. The flowers are more for show, as they do not have a fragrance to them. The plants are not toxic to pets or humans according to the ASPCA website. However, a mild stomach ache could occur if humans consume any part of the plant.

II. How to Grow and Care

Chinese snowball viburnum is hardy in most of the South and semi-evergreen in the warmest growing zones. Give it plenty of space, planting in fall at the back of the border as a large shrub or hedge or in your garden as a small specimen tree. This disease-resistant and highly ornamental shrub will happily adapt to most soils and lighting conditions, making it a popular planting in Southern gardens.

Sunlight

Plant in full sun (at least six hours of direct sunlight per day) or partial shade (two to six hours of sun). To discourage wilting on hot days, provide some protection from the afternoon sun in the Lower and Coastal South.

Temperature and Humidity

Chinese snowball viburnum may not tolerate drought, but this shrub can handle heat and humidity, especially if afternoon shade is provided.

This viburnum is not reliably hardy in zone 6. If you live in the Upper South, plant your shrub in a sheltered location that will protect it from winter winds.

Watering

Viburnum prefers moist soil. This plant can handle some dryness once established, but is not drought-tolerant. Water regularly until established and weekly during hot, dry periods. Mulch around the base of the plant to help preserve moisture.

Soil

Chinese snowball viburnum prefers well-drained, loamy, acidic soil. However, this shrub is fairly adaptable to clay and sandy soils as well as neutral and slightly alkaline soils.

Fertilizing

Fertilizing is not required and this plant does not need heavy feeding. Too much fertilizer can harm the plant and promote rotting. If you do choose to fertilize the plant, use a balanced 10-10-10 fertilizer designed for woody material. Apply during early spring.

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

Be sure to prune after the flowers have died in the early summer. Do this every 3 to 5 years to rejuvenate the plant. Remove the oldest and fattest stems all the way to the ground, which will allow the younger stems to produce the best looking flowers. You can also do light trimming on the plant every year, by lightly shaping the plant and removing any dead branches. Pinch or deadhead spent blooms to help promote new growth.

Spacing

For an informal hedge or mass planting, space this shrub out at least 18 feet on-center. For a more formal, dense hedge, plant shrubs 12 to 15 feet center-to-center. These require very large garden planters if you choose to grow these in a container, but it can be done if there is good drainage and enough room for the plant to grow.

Propagation

Because Chinese snowball viburnum does not typically produce seeds, this plant is propagated from cuttings. Take cuttings in the spring, when soft green stems have sprouted on your shrub:

  • Using sterilized, sharp pruners, cut the green portion of a stem or stems into 4-to-6-inch lengths.
  • Remove the bottom leaves from each cutting, leaving one set of leaves at the top.
  • Dip the bottom tip of each cutting in root hormone.
  • Stick the bottom of each section of stem into a pot filled with moistened potting mix.
  • Cover each pot with a clear plastic bag to conserve moisture and humidity.
  • Place pots in bright, indirect light. Spray with water as needed to keep soil moist.
  • After two to four weeks, the cuttings should be rooted (a gentle tug can confirm that the plant is developing a strong root system). Remove the plastic bag and continue to water regularly, transplanting into a larger pot if needed.
  • Begin to acclimate your plant to the outdoors, first moving it to a protected area. Once the plant is well acclimated and new growth is apparent, you can transplant the shrub. If you plan to move your plant into full sun, it may be best to wait and do so in the fall.

Overwintering

Plant Chinese snowball viburnum in an area protected from freezing winds in the coldest regions. Add a thick layer of mulch to help moderate soil temperature.

Pests and Diseases

Chinese snowball viburnum is known for good disease resistance to bacterial leaf spots and powdery mildew. If your viburnum is under stress and develops leaf spots (light brown or reddish spots), powdery mildew (a white or gray, powdery coating on leaves) or downy mildew (green spots that eventually turn brown), these fungi generally don’t harm the plant and can be controlled by avoiding overhead watering and reducing overcrowding. If you need to spray with a fungicide, avoid any products with sulfur, which is toxic to viburnums.

Stressed plants can be infested by soft green aphids, thin and dark flower thrips, or tiny spider mites. Spray foliage with a strong stream of water from the garden hose to remove insects and remove weeds or cut grass around the base of the plant. If the infestation becomes problematic, use an insecticidal soap.

Deer will generally leave this shrub alone.

III. How to Get Chinese Snowball Viburnum to Bloom

Chinese snowball viburnum flowers in spring, sometimes reblooming in late summer or fall. The flower buds are produced on the previous year’s wood. Make certain to prune the plant just after flowering to avoid removing the next year’s blooms.

Too much shade could prevent or reduce blooming. Consider increasing sun exposure if your plant is in a shady spot.

III. Uses and Benefits 

Primarily grown for its ornamental value, Chinese Snowball Viburnum is perfect for large flower borders, as a specimen plant, or even for forming a loose privacy screen. Its cut flowers are also a popular choice for arrangements.

Alongside its stunning aesthetic appeal, the plant serves as an attractor for pollinators. Its relatively low maintenance requirements and resistance to most pests and diseases make it an excellent choice for both novice and experienced gardeners.

Chinese Snowball Viburnum (Viburnum macrocephalum) Details

Common name Chinese Snowball Tree, Chinese Snowball Viburnum
Botanical name Viburnum macrocephalum
Plant type Shrub
Hardiness zone 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Medium
Height 6 ft. 0 in. - 25 ft. 0 in.
Width 6 ft. 0 in. - 25 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Green
Leaf color Green