Common Hazel (Corylus avellana)

Common hazel (Corylus avellana) is a deciduous shrub species that is cultivated for its edible nuts. Hazelnuts can refer to the nut from any Corylus species, but it most often refers to Corylus avellana. The nuts from common hazel are eaten straight or used in making confectionery. Common hazel is native to Europe and western Asia.

I. Appearance and Characteristics

Corylus avellana, the common hazel, is a species of flowering plant in the birch family Betulaceae, native to Europe and Western Asia. It is an important component of the hedgerows that were, historically, used as property and field boundaries in lowland England. The wood was traditionally grown as coppice, with the poles cut being used for wattle-and-daub building, and agricultural fencing.

Common hazel is mainly cultivated for its nuts. The name ‘hazelnut’ applies to the nuts of any species in the genus Corylus, but (in commercial settings) a hazelnut is usually that of C. avellana. This hazelnut or cob nut, the kernel of the seed, is edible and used raw or roasted, or ground into a paste. The cob is round, compared with the longer filbert nut.

Common hazel is typically a shrub reaching 3–8 metres (10–26 feet) tall, but can reach 15 m (49 ft). The leaves are deciduous, rounded, 6–12 centimetres (2+1⁄2–4+1⁄2 inches) long and across, softly hairy on both surfaces, and with a double-serrate margin. The flowers are produced very early in spring, before the leaves, and are monoecious with single-sex wind-pollinated catkins. Male catkins are pale yellow and 5–12 cm long, while female flowers are very small and largely concealed in the buds with only the bright red 1–3 millimetres (1⁄16–1⁄8 in) long styles visible.

The fruit is a nut, produced in clusters of one to five together, each nut held in a short leafy involucre (“husk”) which encloses about three-quarters of the nut. The nut is roughly spherical to oval, 15–20 mm (5⁄8–3⁄4 in) long and 12–20 mm (1⁄2–3⁄4 in) broad (larger, up to 25 mm long, in some cultivated selections), yellow-brown with a pale scar at the base. The nut falls out of the involucre when ripe, about 7–8 months after pollination.

It is readily distinguished from the closely related filbert (Corylus maxima) by the short involucre; in the filbert the nut is fully enclosed by a beak-like involucre longer than the nut.

II. How to Grow and Care

Sunlight

Placing a hazel in a location that receives full sun most of the day will give you the best yield of flowers and nuts if that is what you are trying to achieve. It will tolerate part shade as well, but you will see a decrease in flower production.

Temperature and Humidity

Hazels thrive in temperate climates in USDA zones 4-8. They don’t do well when exposed to extremes, either winter old, summer heat, or high humidity. Wind, on the other hand, is not an issue, in fact, for pollination, they need windy conditions. But that is the only extreme they resist well.

Watering

Keeping your hazel tree watered is important to ensure profuse flower and nut production. It will not tolerate drought and will need supplemental watering to remain a viable producer if you look forward to it fruiting during dry periods. Water it using the standard rule to establish: 10 gallons per inch of trunk diameter every week after planting. Using this method will keep your hazel green and blossoming in even the driest of weather.

Soil

The hazel tree is very adaptable, but it is best to avoid densely packed soils, clays, or rocky soils. Its preference would be to grow in sandy loams that drain rather well.

Fertilizing

For the best blooms and fruit production, give your tree an application of organic slow-release fruiting tree fertilizer in the fall. For the amount to use, follow product label instructions.

Planting Instructions

Plant trees during their dormancy in the late fall or early spring.

The location should get at least 8 hours of full direct sunlight every day. In terms of soil quality, the hazelnuts are adaptable but the soil needs to be rich and well-drained with a slightly acidic pH between 6.3 and 6.8.

Space the trees 15 to 18 feet apart. For planting, dig a hole wide and deep enough to accommodate the J-shaped root system. Place a small amount of soil in the hole and spread out the roots. Cover the top root with 2 to 3 inches of soil (hazelnut roots grow close to the soil surface). Add a couple of additional inches of soil to allow for the soil to settle without exposing the top roots. Tamp down the soil and water deeply.

Because hazelnut trees develop multiple stems, staking is not needed. But to protect the young plant against deer browsing and other wildlife, use a mesh tree guard for the first few years.

Pruning

The primary upkeep task for a hazelnut tree involves cutting away the suckers that all hazels develop. You may actually want this dense growth if you are using your hazel to attract wildlife and birds. The sucker growth will create a thicket and give shelter and a habitat to the critters and feathered friends when they need it. For a neat appearance, which also makes harvesting easier, cut the sucker growth and create a brush pile with it as a shelter. The cuttings are fantastic for all kinds of crafts, from basketry to wreath-making.

Be careful not to confuse suckers with lateral branches. Don’t remove any branches that shield the trunk from sun exposure, or you will end up with irreversible, prolific sprouting.

Propagation

Hazelnut trees are typically layered or grafted, a job that is best left to nursery professionals. As they are propagated by vegetative methods, growing them from seed is not recommended.

Overwintering

The European hazelnut tree is able to survive winters as low as Zone 4 but because it blooms earlier than its American counterparts, it may be damaged by unseasonably cold early spring weather. Some varieties are hardier than others; follow the nursery’s recommendations for the varieties that work best in your geographical area.

Pests and Diseases

The most common serious issue affecting European hazelnuts is Eastern filbert blight (EFB), a fungus that causes cankers and kills the tree within a few years. Select cultivars that have been bred for resistance against the diseases.

Pests include scale and Japanese beetles which may defoliate the plant.

III. Uses and Benefits

• Ornamental uses

Common hazel is a shrub and tree cultivated commercially for its edible nuts. It serves as a privacy plant in hedges, plant screens, and borders. It is ideal in naturalized garden spaces like cottage or prairie gardens, meadows, and woodlands.

• Culinary uses

Hazelnuts are rich in protein and unsaturated fat. They also contain significant amounts of manganese, copper, vitamin E, thiamine, and magnesium.

Common hazel is cultivated for its nuts in commercial orchards in Europe, Turkey, Iran and Caucasus. The name “hazelnut” applies to the nuts of any of the several species of the genus Corylus. This hazelnut or cobnut, the kernel of the seed, is edible and used raw or roasted, or ground into a paste. The seed has a thin, dark brown skin which has a bitter flavor and is sometimes removed before cooking. The top producer of hazelnuts, by a large margin, is Turkey, specifically the Giresun Province.

IV. Harvesting and Storage

Ripe nuts drop on their own over the course of a few weeks. Either collect the nuts on a regular basis before wildlife snaps them up or place a tarp or old sheet below the hazelnut bush and gently shake it to loosen the nuts.