Corylus

Hazels have a traditional appeal and fulfil a range of roles in gardens and landscapes

Corylus avellana 'Fuscorubra' - photo: Graham Clarke
Corylus avellana 'Fuscorubra' - photo: Graham Clarke

Country folk have always put hazel (Corylus spp.) to a wide range of uses. The wood is not long-lasting, but because the rods are both pliable and abundant they have been used for many purposes: baskets, wattle and daub frames, hurdles and fencing panels, thatching spars, hoops, fishing rods, walking sticks, broom handles and so on. Forked hazel twigs are the traditional tool for water divining. But these days landscapers are increasingly using them for their decorative qualities.

Most forms of Corylus provide useful colour from January onwards. All are deciduous, broad-leaved shrubs or trees. The Turkish hazel, C. colurna Award of Garden Merit (AGM), is the largest species, forming a tree of up to 10m high with a spread of 8m when mature.

Most hazels can be grown as ornamental shrubs, and they make fine specimen subjects, border plants and hedging. Arguably the two best forms for decorative landscaped areas are C. avellana 'Contorta' AGM and C. avellana 'Pendula', both low-growing, medium-sized shrubs.

Hazel, to most people, calls to mind the nuts of the British native C. avellana, which are also known as cobs. These are ovoid and about 2cm long, and protected by bracts, appearing in clusters of between one and four. Slightly larger "filberts", fully enclosed in husks, are produced by the closely related and similar-looking C. maxima.

Generally, it is the male flowers, appearing as long, pendulous catkins, that are the most attractive features of the genus, particularly in late winter and early spring. These are carried at the end of branches to disperse the pollen more easily through the action of the wind. Female flowers are very small and usually only the red stigmas are visible. They appear toward the centre of the plant and give rise to the nuts.

In contrast, the rarely seen Japanese hazel, C. sieboldiana, is hermaphrodite, bearing flowers with both male and female parts.

Most forms of Corylus are hardy, surviving temperatures as low as -22 degsC. They grow in most conditions although a loamy soil is preferred. They will also tolerate exposed sites, some shade and thin, chalky soil.

Corylus can be pruned to keep its size down, but this is not suitable for very small gardens. Pruning should be light until the plant has matured. After this period pruning can be slightly heavier and should be carried out after flowering has finished.

What the specialists say

Keith Sacre, sales manager, Barcham Trees, Cambridgeshire:

"We have small supplies of several forms of C. avellana, but our main experience is of Turkish hazel, C. colurna Award of Garden Merit (AGM). It's large and imposing, rather columnar when young before broadening to a symmetrical pyramid on maturity, and has a roughly textured, corky bark. It also produces long catkins in early spring and clusters of fringed nuts in the autumn.

"It is a good choice for an urban site as it's tolerant of pollution and it doesn't react badly in a paved situation. It also doesn't mind whether the soil is chalk or clay either.

"I think its main fault is that it tends to get on the large side, making urban planters nervous. In a parkland setting, however, it is outstanding.

"It is mainly sold in 12-14cm and 20-25cm girth sizes, or 45-litre and 150-litre pots, and the customer base for it is fairly equal between private landscapers and local authorities."

Tara Handley, plant manager, Buckingham Nurseries, Buckingham:

"Some 30 per cent of our customers are landscape designers and there is a steady requirement for forms of Corylus, albeit mainly for hedging. In my experience the straight species C. avellana is most popular - it's thought to be more traditional and therefore a better plant for hedging, where quantities of plants are being sold. If someone wants a more decorative hedging form then they'll go for C. avellana 'Aurea' or C. maxima 'Purpurea' AGM.

"In terms of growing Corylus for its nuts, the filberts are not as popular as walnuts (Juglans spp.), but there is a steady requirement for 'Cosford' and 'Kentish Cob', which are both good fruiting plants.

"If any landscaper or specifier needs to know the quantity of Corylus required for a run of hedge, they just need to check the plant calculator on our website, www.hedging.co.uk. We sell our hedging plants as field-grown bare-roots and they are dispatched between November and March."

In practice

Wolfgang Bopp, curator, Sir Harold Hillier Gardens, Hampshire:

"C. avellana 'Contorta' stands out as being the most interesting form. It provides a good display all year round, but in winter when the stems are bare, displaying the twisted stems in all their glory, it really is a stunning plant.

"We hold the National Collection of decorative Corylus, comprising nearly 30 forms, and we are in the process of planting up a coppice area.

"It is gratifying to see lots of interest in hazels generally at the moment, and there's a distinct sense that more people are growing them in order to retain the old country crafts of coppicing for hurdles and thatching."

Species and cultivars

  • C. avellana is our native common hazel or cobnut, forming a large shrub or small tree. It produces long, yellow catkins in February, followed by mid-green foliage turning yellow in autumn. One of the HTA's "Top 100 Shrubs for Amenity Landscapes", it is also ideal for hedging.
  • C. avellana 'Anny's Compact Red' is a fairly recent introduction, with deep red young foliage and purple catkins in March/April. It grows to just 2m in 10 years.
  • C. avellana 'Aurea' makes a large shrub with yellow foliage all season.
  • C. avellana 'Casina' is a recently introduced variety recommended for garden planting. It produces good crops of small, thin-shelled nuts with a good flavour.
  • C. avellana 'Contorta' is also known as the corkscrew hazel, and Harry Lauder's walking stick. Its branches are twisted, making it a striking plant, particularly when clothed in pale yellow catkins in mid to late winter. It is slow growing and is smaller than the species.
  • C. avellana 'Corabel' is a recent French selection. It is a vigorous upright bush, producing heavy crops of good-quality nuts.
  • C. avellana 'Cosford Cob' produces medium-sized, thin-shelled nut with a sweet flavour. It is an upright, fairly vigorous hardy tree and produces abundant pollen, making it a good pollinator for other cultivars.
  • C. avellana 'Fuscorubra' is more of a large, multi-stemmed shrub than a tree. Muted pink and green catkins appear in late winter and early spring, followed by rich purple leaves ideal for contrast in informal planting schemes. The nuts are edible.
  • C. avellana 'Pearson's Prolific' has a compact habit. It produces abundant crops of small to medium-round, flavourful nuts and is a good pollinator. It is often sold as 'Nottingham Prolific'.
  • C. avellana 'Pendula' is a weeping form that grows only to the height to which it is supported.
  • C. avellana 'Red Majestic' is a relatively new purple-leaved, contorted hazel. It is a medium to large, upright shrub with intricately contorted twigs, large purple catkins in late winter and rich purple foliage turning green as it matures. Purple, edible nuts form in summer.
  • C. colurna Award of Garden Merit (AGM) is the Turkish hazel. It has broad, green leaves and ribbed bark, and produces yellow catkins. It will form a pyramid-shaped tree of up to 10m in height.
  • C. x colurnoides 'Laroka' has the common name of trazel. It produces long nuts of good size and flavour. The tree is vigorous with large, dark green leaves. It tolerates strong winds but not maritime exposure.
  • C. maxima is also known as the filbert. It forms a large, vigorous, bushy, open shrub or small tree. It has large, rounded leaves and reaches about 6m tall.
  • C. maxima 'Butler' is a medium size tree, producing heavy crops of large, strongly flavoured nuts. It is a large, mid- to late-season variety.
  • C. maxima 'Garibaldi' is an old variety with large leaves, producing crops of long, thin-shelled nuts. It makes an attractive, large, spreading shrub.
  • C. maxima 'Halle'sche Riesennuss' is an attractive large spreading shrub, growing to 4-5m.
  • C. maxima 'Kentish Cob' is also sometimes sold as 'Lambert's Filbert' and is a traditional cobnut from Kent.
  • C. maxima 'Purpurea' AGM is a large, vigorous, open shrub or tree, with large, round, deep purple foliage. The catkins are purplish with yellow anthers hanging from bare branches in February.
  • C. maxima 'Red Filbert' is a large, bushy shrub, whose wine-red leaves are almost translucent in the sun. It is sometimes also sold as 'Roter Zellernuss'.
  • C. 'Te Terra Red' has purple foliage that keeps its colour into autumn. The nuts of this recently introduced cultivar are also purple. The bark is corky and attractively fissured.

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