RHS Garden Harlow Carr

Plant of the month: May

Daphne retusa @ Harlow Carr

When you pass through the entrance to the gardens turn right at the bottom of the steps and continue along the path to the alpine glasshouses. Turn right onto the path in front of the first display glasshouse and follow the path round to the second smaller aluminium glasshouse. Daphne tangutica Retusa Group is in the raised bed in front of this glasshouse.

Daphne

Daphne as a genus consists of about 50 deciduous, semi-evergreen and evergreen species from Europe, North Africa and Asia. Their natural habitats range from lowland woodlands to mountains. Plants that grow at higher altitudes are often deciduous while plants from lower altitudes are evergreen but less hardy.

The name Daphne may be derived from an Indo-European root meaning ‘odour’. However, according to Greek mythology, the plant was named after a nymph who was changed by the gods into a bay tree to save her from pursuit by Apollo; Daphne is the Greek name for a bay tree.

A wide range of Daphne species and cultivars are grown for their delightfully fragrant flowers, which most have in abundance, but some are grown for their foliage, fruit or upright, rounded or prostrate habit. Many are at their best in the depths of winter making them of great horticultural value. They vary in hardiness as well as leaf retention, flowering period and shade tolerance.

Daphnes grow well in borders or in woodland settings and once planted do not like to be moved. They will also perform well in containers. To gain the maximum pleasure from growing daphnes, plant them near paths and buildings where both the sight and scent of their flowers can be easily admired and appreciated.

All parts of the plant are poisonous and skin contact with the sap can cause dermatitis in some people.

Daphne tangutica Retusa Group

This species from Western China is one of the finest shrubs for the rock garden or the front of a shrub border. It was discovered by A E Pratt in 1889 in Western Szechuan.

It is a compact, dwarf, evergreen shrub, with oval, glossy, leathery, dark green leaves up to 5cm (2in) long that are notched at the tips. The name Retusa means ‘with a rounded, slightly notched tip’.

In late spring and early summer, fragrant flowers are borne in densely crowded terminal clusters of up to 10 flowers. Their colour is white inside and purple-red outside and they are up to 1cm (0.5in) across. The flowers are followed by fleshy, red berries.

AGM

The RHS Rock Garden Plant Trials Subcommittee awarded Daphne tangutica Retusa Groupan Award of Garden Merit and described it as a: Small evergreen shrub of dense, rounded habit, with short dark green elliptic leaves and terminal clusters of fragrant flowers, nearly white within, purple on the outside. Red berries.

Cultivation

Grow in moderately fertile, humus-rich, well drained but not dry soil. The acidity should be between slightly alkaline and slightly acid.

Plants are resentful of root disturbance and should be planted into their permanent positions as soon as possible.

Aphids, leaf spot, grey mould (Botrytis) and viruses may be a problem.

Propagation

Seed is best sown in a glasshouse as soon as it is ripe with the pot sealed in a polythene bag to hold in moisture. Remove this bag as soon as germination takes place. Germination should normally occur by spring, although it sometimes takes a further year. Prick out the seedlings into individual pots as soon as they are large enough to handle. Grow the plants on in a glasshouse for their first winter and then plant out in spring after the last expected frosts.

Cuttings of half-ripe wood with a heel can be taken in June or July and put in a frame.

Propagation may also be achieved by the division of suckers, or layering.