Growing sweet viburnum bushes (Viburnum odoratissimum) adds the delightful element of fragrance to your garden. This member of the large viburnum family offers showy, snowy, spring blossoms with a very appealing scent.
I. Appearance and Characteristics
Viburnum odoratissimum, commonly known as sweet viburnum, is a shrub or small tree in the family Adoxaceae. It is native to Asia, and commonly cultivated as a garden ornamental elsewhere.
The extremely fragrant flowers of the sweet viburnum are tiny, but the shrub is enormous. At 20 feet (6 m.) tall, it qualifies as a small tree. In springtime, the entire canopy is covered with the tiny blossoms. This has long made it a landscape favorite. Growing sweet viburnum bushes is recommended in warmer regions of the country, like coastal areas. The species thrives in USDA plant hardiness zones 8b through 10a. According to sweet viburnum information, this area includes the southern coast from Florida through eastern Texas and the entire Pacific Coast.
If you are thinking of growing sweet viburnum bushes, you’ll want to figure out optimal sweet viburnum growing conditions. The tree thrives in either full sun or partial shade, and accepts almost any type of soil, including clay and sand, as long as it drains well. It does well in both acidic and alkaline soil. On the other hand, ideal sweet viburnum growing conditions do not include salty soil. It also has low aerosol salt tolerance.
II. How to Grow and Care
Viburnum odoratissimum is an evergreen shrub that grows best outdoors, in full sun, with moist soil and reasonable drainage, so finding the right position is key to your success, and beyond that, it’s all about simple maintenance.
Sunlight
Sweet viburnum in a cold environment 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
The optimum growth temperature range is between 5 to 27℃. It has good cold resistance; some native North American species can tolerate temperatures below -25℃. Its growth is poor at temperatures above 29 ℃, so it cannot survive in tropical summers. Germination requires 20 consecutive days of seed exposure to 24℃.
Sweet viburnum needs occasional watering during hot and dry conditions. The average plant during its first 2 years of growth needs 1.2 to 1.5 cm water bi-weekly. Once established, it doesn’t need much watering.
Watering
Moist soil makes sweet viburnum more vigorous. Insufficient water decreases the ornamental value of the whole plant and leads to abnormal flowering. Water management is the key to survival during transplanting. The newly transplanted plants must be irrigated continuously for 3 – 4 weeks to ensure that the soil is fully absorbent and closely connected with the root system.
During severe hot and dry conditions, 7 to 8 mm of water weekly is sufficient. In daily maintenance, just keep the soil moist. Too much soil moisture affects air permeability, inhibits root respiration, causes rotten roots, and even causes the plant to die in severe cases.
Soil
Sweet 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. Sweet 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.
Mulching
Mulch Viburnum odoratissimum annually with any neutral compost, or well-rotted manure. There is no need to fertilize in the garden provided it is mulched annually.
If you don’t mulch, you can boost the nutrients for better fragrance with any flower focussed fertilizer, but I like liquid seaweed as a balanced organic feed for flowering shrubs.
Propagation
Viburnum odoratissimum does produce viable seeds in the form of berries, which are ripe and ready to sow when they turn black in autumn, but the easiest (and fastest) way to grow new plants is through greenwood cuttings.
Take semi-ripe greenwood cuttings from Viburnum odoratissimum in early or mid-summer when this year’s growth has had time to grow to 3-4” long, and have young leaves at its tip.
Trim any old large leaves, so there is 3” of stem to bury below the soil, and carefully cut off ½ of the youngest leaves to prevent evaporation. Follow that step by pushing your cuttings into a small plastic pot filled with a 50:50 mix of vermiculite and cutting compost.
Water well, then leave in a cold frame or greenhouse until new growth appears. For a more detailed guide on taking greenwood cuttings read our ultimate guide to taking cuttings.
Transplanting
The ideal season for transplanting sweet viburnum is mid to late summer when vibrant growth prevails. Ensure the new location receives plenty of sunlight and well-draining soil. Keep the sweet viburnum’s roots constantly moist for an effortless transition.
Pests and Diseases
Viburnum odoratissimum is a tough plant, with very few pests or disease problems, particularly in Australia, but like any garden shrub, their new growth in spring is very susceptible to aphids and ants.
Aphids
odoratissimum occasionally suffers from aphids on new shoots in spring but they cause little harm. If you notice blackening tips on new growth, wash aphids off with a powerful hose
Ants
Ants adore viburnum of all varieties, but once your plants have been established they will cause little to no harm to the plant. For young plants, rub a small amount of Vaseline over the trunk once every 4 to 8 weeks in spring and summer to stop them from climbing.
Dry leaves
The only common problem with V. odoratissimum is dry leaves from wind or drought. They are completely happy in full sun but need good moisture through summer.
Unlike most viburnums that can cope with dry shade all year round, V. odoratissimum is a little pickier about its position.
While drought can cause dry or frazzled leaves, the most common cause is actually wind. They prefer a sheltered position and should be kept well away from any sea breeze as the salty winds can dry out their luscious leaves.
III. Uses and Benefits
Sweet viburnum has many varieties, suitable for various garden sites, including flowerbeds in shady or sunny locations. It is available in a variety of flower and berry colors to match many landscape designs. It grows as a shrub or tree with year-round appeal, producing attractive flowers in spring, ornamental berries in the fall, and vibrant orange or red foliage for autumn color.
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