Hazelnut

Hazelnut is grown as a long-lived perennial planting, established from rooted suckers, layered plants, or grafted material depending on region and cultivar. Its distinctive early flowering habit and reliance on wind rather than insects for pollination set it apart from most other temperate tree nut crops.

Production ranges from traditional shrub-form plantings managed with multiple stems to single-trunk, tree-form orchards designed for mechanical harvest, with the choice shaped by regional tradition, labor availability, and equipment.

Family

Betulaceae (birch family)

Genus

Corylus

Principal species

Corylus avellana (common hazel)

Pollination mechanism

Wind-pollinated; male catkins release pollen carried by air movement to separate female flowers on the same or nearby plants

Flowering biology

Often dichogamous, with male and female flower maturity on an individual plant offset in time, favoring cross-pollination from other cultivars

Growth habit

Deciduous, multi-stemmed shrub by nature; commercially grown either as a shrub or trained to a single trunk

Corylus avellana is native to Europe and parts of Western Asia, where it has long grown wild in woodlands and hedgerows in addition to being cultivated. Commercial production has since expanded to other temperate regions with suitably mild winters.

Current production statistics, leading cultivars, and trade patterns shift over time and by region; up-to-date figures are best obtained from primary sources such as FAOSTAT and national agricultural statistics services rather than assumed.

Hazelnut requires a period of winter chilling to flower normally, but is distinctive among temperate tree nuts in flowering in winter or very early spring in many growing regions, well ahead of most other tree crops. This early bloom timing means frost during the flowering period is an important site consideration, even though the exact timing varies by region and cannot be generalized to a specific calendar window.

Because pollination depends on wind rather than insects, calm, dry conditions during the bloom period support effective pollen dispersal, while prolonged wet or very windy weather can reduce pollination efficiency.

Hazelnut performs best on deep, well-drained soils with good structure; loams and sandy loams are generally favored. The crop has limited tolerance for waterlogging, which restricts rooting and increases the risk of root diseases.

Establishing a hazelnut planting begins with choosing between a shrub-form or single-trunk training system, a decision shaped by regional tradition and whether mechanical harvest is planned. Because of dichogamy and reliance on wind pollination, cultivar selection places significant weight on interplanting two or more cultivars whose male and female flowering periods complement one another across the planting.

• Training system selection: multi-stemmed shrub versus single-trunk tree form
• Cultivar selection considering dichogamy and interplanting for pollination timing
• Sucker management, which is more intensive in shrub-form plantings
• Long-term canopy and orchard floor management across many productive years

Nitrogen supports vegetative growth and nut development, while potassium contributes to overall plant vigor and nut fill. Boron is a micronutrient of particular relevance to hazelnut, since deficiency can affect flowering and nut set.

Hazelnut is grown both rain-fed and under irrigation depending on region, with water demand rising through nut development. Drip irrigation is widely used in modern plantings to apply water efficiently to the root zone.

Irrigation scheduling aims to avoid water stress during sensitive growth stages while preventing waterlogging, which hazelnut tolerates poorly.

Anthracnose can affect leaves, shoots, and developing nuts under humid conditions. Root rot, often linked to poorly drained or waterlogged sites, can weaken plants over time. Among insect pests, weevils — including the hazelnut (nut) weevil, Curculio nucum, a well-documented hazelnut-specific pest — can damage developing nuts, while aphids and mealybugs can affect foliage and shoot growth.

Management combines resistant or tolerant cultivars where available, orchard sanitation, monitoring, and — where justified — locally authorized control products applied according to their labels.

Hazelnut is harvested once nuts have matured and dropped from the husk, either naturally falling to the ground for mechanical sweeping and collection or, in some systems, gathered from the plant. Nuts are then dried to a moisture content suitable for storage and processing.

• Raw and roasted kernels for direct consumption
• Confectionery uses, including chocolate-hazelnut products and baking ingredients
• Hazelnut oil pressed from the kernel
• Processed products such as hazelnut paste and flour