Culture
Best grown in moist, organically rich, well-drained soils in full sun to part shade. Tolerates average garden soils. Avoid heavy clays. 'Red Dragon' is often sold as a grafted specimen attached to a Corylus avellana rootstock. Promptly remove root suckers to help maintain plant appearance and prevent thicket formation. Also prune out any stems that have reverted and lost their purple leaf color or twisting form.
Noteworthy Characteristics
Corylus avellana, commonly called European filbert, European hazelnut or cobnut, is a deciduous, thicket-forming, multi-trunked, suckering shrub that typically grows to 12-20’ tall. It is native to Europe, western Asia and northern Africa where it is typically found growing in rich thickets, woodland borders, wooded slopes, hedgerows, clearings and along streams. Monoecious flowers (separate male and female flowers on the same plant) bloom on bare branches in late winter to early spring (February-March) before the leaves emerge. Somewhat showy, pale yellow-gray male flowers appear in sessile drooping catkins (each to 2-3” long). Inconspicuous female flowers with red stigmas bloom just above the male catkins. Double serrate, elliptic to ovate to orbicular, medium green leaves (to 4” long) are rounded to cordate at the base and generally hairy. Leaves turn variable but often unexceptional shades of yellow in fall. Smooth light bark is gray-brown. Fruit is a hard edible brown nut (to 3/4” long) enclosed in a leafy, hairy, light green husk. Nuts are known as cobnuts. Nuts appear in terminal clusters of 1-4 and are half covered in ragged husks. The husk (involucral tube) surrounding the nut extends beyond the nut by at least one inch to form a beak. Nuts ripen in late August and September. In Europe, cultivars of this shrub are commercially grown for nut production. Numerous cultivars exist. In the U.S., Oregon is the center for nut production.
Genus name comes from the Greek word korylos, or from korys meaning a helmet, in regard to the husk on the nut.
Specific epithet comes from Avella Veccia (southern Italy) or of Avellino (city east of Naples where this plant was much cultivated and called nux Avellana by the Romans).
Common names of filbert and hazelnut are likely interchangeable. Hazelnut is more often used in reference to wild specimens and filbert is more likely to be used in reference to cultivated plants. The filbert nuts produced in commerce primarily come from hybrid plants (C. avellana x C. maxima).
'Red Dragon' is a moderately vigorous, purple-leaved selection of European hazelnut that will reach around 6' tall with an equal spread in 10 years. The foliage emerges in spring a dark burgundy to maroon color, and maintains this deeply saturated tone through summer. The catkins, which emerge in late winter, are also somewhat red in color. 'Red Dragon' features twisted or "contorted" branching, and the leaves also have a wavy or curled appearance. Will sometimes be sold under the common name "contorted filbert" or "contorted hazelnut". A few nuts may be set if a compatible pollen donor is nearby, but this selection will not self-pollinate. Protected by patent number PP20694.
Problems
'Red Dragon' offers increased resistance to filbert blight. Infrequent disease problems include black knot, crown gall, apple mosaic virus, and leaf spot. Scale may occur. Japanese beetles may vigorously attack the foliage in some areas.
Uses
Specimen tree for mixed borders and woodland edges. Use as a structural anchor for foundation plantings.