Thegenus includes a very wide variety of evergreen and deciduous shrubs, flowering in winter, spring and summer. Some are grown for their , some for their berries, some for their colourful autumn , and some for all three. Certain species are best grown as bushes, but many make excellent wall shrubs – although most viburnums are hardy, they flower earlier and better on a wall or fence. V. x burlcwoodii is a spreading semi-evergreen or evergreen which grows to about 2.1 m (7ft) and bears dusters of fragrant white from March to May.
There are a number of named varieties with slight differences of lower size and habit of growth. V. farreri, formerly known as V. fragrans, is a deciduous winter-flowering species. It grows to 3m (10 ft) or more against a wall, and bears its fragrant white and pink flowers from November to March intermittently, in spells of fine weather. Thefollow the flowers in spring. ‘Candidissimum’ is a variety with all-white flowers, and brighter green leaves.
V. grandzflorum is similar to V. farreri and, as its name suggests, its flowers are bigger. They are also pinker, and come slightly later, in December, but last until April. V. rhytidophyllum is an upright evergreen species, 3.6m (12 ft) tall, with whitish flowers in May and June followed by red berries that turn black when ripe. If this species is grown for the berries, you must have at least two plants, one male and one female.
V. x bodnantertse is a useful hybrid of V. farreri and V. grandiflorum, since it is more vigorous, growing to 3.6m (12 ft) and hardier than either. It is deciduous, and carries white-pink fragrant flowers on the bare wood, sometimes from October to February. ‘Dawn’ is the cultivar usually available, but ‘Deben’ has a longer winter-flowering period than any, going from October to April if the weather is mild.
General care: Viburnums like a moist, rich soil, with somedug in, and a mulch of mould from time to time. Plant deciduous varieties any time in the winter, and evergreens in April, in. A south-facing wall is ideal. Vibumums do not need regular : any tidying up needed should be done when they have finished flowering.
Propagation: Growing fromis not satisfactory. It is best to take at the end of the summer and them in a 50-50 sand and peat mixture. Or shoots layered at this time will be ready for separating a year later.
Pests and diseases: Frost-damaged shoots sometimes die back. In spring, cut back to sound wood. Fungi sometimes cause spots on the leaves, and if troublesome can be sprayed with a fungicide.
V. opulus, the Guelder rose, is a deciduous shrub up to 4 m tall, which flowers in May. It has limp, three-lobed leaves, bare or hairy on the underside, bunches of small, fertile flowers and large, white sterile flowers, and pendent clusters of red berries; ‘Compactum’ is a bushy shrub, up to 1 m tall with large, bright red berries; ‘Notcutt’s Variety’ has fresh green leaves, broad clusters of white flowers, and bright red berries; ‘Roseum’ (syn. ‘Sterile’) is an upright shrub with spherical heads consisting only of green or snowy-white sterile flowers; for sun or (semi-)shade in moist, lime-rich soil; drought encourages.
V. plicatum, Japanese snowball tree, is a deciduous, broad shrub up to 3 m tall, which flowers in May-June. It has spreading shoots, oval leaves, 7-12 cm long, folded between the veins and hairy on the underside, turning purplish-red in the autumn, and spherical heads of white, sterile flowers. Many cultivars also have berries, such as ‘Mariesii’, up to 1.5 m tall and 3-4 m broad, with larger, flat heads of white, sterile flowers up to 4.5 cm across. Grow as a specimen plant or in large beds; ‘Nanum Semperflorens’ (syn. ‘Watanabe’), up to 1.5 m tall, flowers for a long time with flat, pure white umbels of flowers. V. rhytidophyllum is a vigorous, evergreen shrub, approximately 3 m tall and broad, which flowers for a long time from early spring. It has soft, dark green, oblong, wrinkled leaves, 10-18 cm long, hairy on the underside, large heads of white flowers and red berries that mature to a brownish-black; it requires a spot sheltered from the wind and should have no morning sun. V. tinus, laurustinus, is an evergreen, upright shrub, 2-4 m tall, which flowers from November-February. It has shiny green, oval, pointed leaves, 3-10 cm long, dark pink buds, whitish-pink flowers and blue berries; it requires a sunny, very sheltered spot in moist, nutritious soil, rich in humus. This shrub requires a sunny or semi-shady spot, and soil rich in humus. Only remove trapped or tangled branches. Propagate from summer cuttings and by.