Corylus (Hazel)

Corylus avellana 'Contorta' with Catkins

A small group of hardy deciduous trees and shrubs, mainly grown for the edible nuts that ripen in the autumn. Most forms have long decorative catkin flowers, which provide good late winter interest.

The male catkins (known as lamb's tales), which appear before the leaves, are long, yellow and rich with pollen. The female flowers are enclosed by a small brown Bracts.

Family: Betulaceae (birch family)
Botanical Name: Corylus (ko-ril-us)
Common Names: Hazel, cobnut, filbert, hale nut, hazelnut
stock nut, wood nut, Constantinople nut, Turkish hazel.

Foliage: Large, rounded, mid-green deciduous leaves that turn yellow in autumn. Purple forms are available.

Flowers: Long male catkins (racemes of yellow flowers). Often followed by hazelnuts in autumn.

Flowering Period: Late winter to early spring

Soil: Moist but well-drained soil (chalk, clay, sand or loam). Alkaline or neutral pH.

Conditions: Full sun or partial shade. Can be grown in any aspect, in either sheltered or exposed locations.

Habit: Spreading, branched.

Type: Large shrub or small tree.

Origin: Europe, Asia, China, Korea, Japan, Siberia, North Africa.

Hardiness: Hardy in all regions of the UK (down to -20 °C).

Planting and Growing Corylus

Shrubby hazels are quite attractive when in flower and during the autumn, but are not much to look at in the summer, except for the purple leaved forms such as C. maxima 'Purpurea'.

Grow in an open sunny position, in any good well drained, fertile soil. Hazels are happy in full sun or partial shade but flower much better in full sun. All forms are tolerant of chalky soils.

An excellent border or specimen shrub, also ideal in an open woodland settings. A good choice for windy sites but not coastal.

Plant field-grown specimens from November to March and container-grown plants at any reasonable time. Position them to achieve the maximize display of catkins in winter. Ideally against a large evergreen backdrop.

Hazels can be underplanted with anemones, hellebores, primroses and other spring flowering plants to good effect.

Taking Care of Corylus

Water thoroughly during dry weather until well established. Mulch with organic matter in spring and apply a balanced, general-purpose, fertiliser each spring.

Pruning Corylus

Regular pruning is not required except for the removal of dead wood and some of the older branches to encourage new fresh shoots. Note: laterals from the previous year carry crop.

Remove suckers from grafted plants as soon they shoot.

Pests and Diseases

Susceptible to attack by aphids, caterpillars, gall mites, sawflies and weevils. Squirrels will eat the nuts.

Mildew can cause defoliation.

Propagating Corylus

Propagate from seed or from rooted shoots taken from the base.

Popular Varieties of Corylus Grown in the UK

Corylus avellana (Common Hazel or Cobnut) has pendant yellow male catkins on bare branches mid-winter. Height to 10ft (3m). Good varieties include 'Aurea' which has soft green foliage, turning yellow with age, and 'Heterophylla' with smaller, deeply lobed leaves.

Corylus avellana 'Contorta' (corkscrew hazel) has interesting twisted branches, covered in late winter with
pale yellow catkins.

Corylus maxima (Filbert) is a large shrub with heart-shaped leaves and large nuts. Height to 10ft (3m).

Corylus maxima 'Purpurea' has decorative purple leaves and catkins.

Corylus colurna (Turkish Hazel) is a giant form that eventually makes a neat 30ft high conical tree.

Corylus chinensis (Chinese hazel) is a large deciduous tree. Flowers from April to May. Eventual height up to 80ft (24m).