Hazelnut

Growing Conditions

Growing Zones

Thrives in USDA Zones 4 - 9

Companion Planting

When to Plant

• Transplant

  Plant bare-root or container stock in early spring or autumn while dormant

• Harvest

  Nuts fall or are shaken from the shrub when husks turn brown, typically late summer to autumn

Organic Growing Tips

• Plant two or more varieties for cross-pollination and better nut set.

• Coppice old stems periodically to encourage vigorous new growth.

• Mulch heavily around the base to suppress weeds and retain moisture.

Common Pests

• Eastern Filbert Blight
• Aphids
• Squirrels
• Filbert Weevil

Taxonomy

Kingdom

Plantae

Family

Birch family (Betulaceae)

Genus

Corylus

Species

Corylus avellana

Natural History

Corylus avellana has one of the longest relationships with human food culture in Europe. Hazelnut shells are among the most common botanical remains found at Mesolithic and Neolithic archaeological sites across Britain and northern Europe, where they appear in quantities suggesting deliberate harvesting and possibly managed coppice stands as early as 9,000 years ago. The genus name Corylus derives from the Greek korylos, meaning helmet, a reference to the leafy involucre — the papery husk — that partially encases each nut. Roman writers including Pliny the Elder described the hazel in cultivation, and it appears throughout Norse and Celtic tradition as a tree of wisdom and otherworldly knowledge, featuring prominently in Irish mythology as the nine sacred hazel trees overhanging the Well of Wisdom. In medieval Europe, hazelnut coppice was formally managed in rotation across large woodland estates; the flexible young poles were essential for wattle fencing, charcoal, and hurdle making, making the hazel simultaneously a food and structural resource. The shrub's botanical behavior matters deeply to growers: hazelnut is wind-pollinated, with male catkins opening in late winter weeks before the microscopic red female flowers appear on the same or a neighboring plant, requiring two genetically different individuals for reliable nut set. This unusual timing — flowering in February or March before any leaf emerges — makes hazelnut one of the earliest pollen sources of the year for queen bumblebees emerging from winter dormancy. The American hazelnut (Corylus americana) is a closely related native species valuable in North American food forest and restoration plantings, and breeders have crossed both species to develop blight-resistant hybrid varieties suited to the Pacific Northwest and upper Midwest.

Traditional Use

Hazelnut has a long presence in European folk botanical traditions, with recorded uses spanning leaves, bark, and nuts. The plant appears in medieval herbal manuscripts and early modern European herbals primarily in the context of the nuts as a nourishing food, while leaves and bark were documented in folk practice across Britain, Germany, and Scandinavia. Hazelnut does not carry the weight of formal pharmacopoeia use, but it is well represented in ethnobotanical records as a household plant with practical non-food applications.

• Medieval European herbal tradition, including Hildegard of Bingen's 12th-century Physica - nuts

  Hildegard described hazelnuts as strengthening to the brain and noted their value as a substantial food for people engaged in physical labor; the nuts appear consistently in medieval European dietary texts as a rich, sustaining food rather than a botanical medicine.

• British and German folk botanical records, 16th–19th century - leaves and bark

  English and German herbalists including John Gerard in his 1597 Herball recorded hazel bark and leaves as astringent materials noted in folk practice; Gerard described the nuts as nourishing but also documented folk belief that the shells and husks had drawing and binding properties when applied externally.

• Scandinavian and Celtic folk tradition - catkins and nuts

  In Irish and Scandinavian folk tradition, the hazel was closely associated with wisdom and divination rather than medicine; hazel rods were used in dowsing and ritual contexts, and the nuts held symbolic status in mythology, placing the plant in a cultural rather than strictly medicinal frame.

Hazelnut is a major tree nut allergen; individuals with tree nut allergies may experience severe reactions. The pollen is also a well-documented cause of seasonal allergic rhinitis across Europe and North America. The nuts, leaves, and bark are not known to be toxic to humans in ordinary food quantities.

This information is provided for historical and educational purposes only and is not medical advice. Always consult a qualified healthcare professional before making decisions related to your health.

Morphology (Plant Structure & Identification)

• Root System

  Hazelnut develops a dense, fibrous surface root system that spreads widely beneath the drip line rather than driving a deep taproot; this means it competes strongly with nearby shallow-rooted plants and is sensitive to soil compaction and cultivation within its root zone. Suckers arise freely from the base and must be removed regularly unless layering propagation is intended.

• Stem

  The shrub produces multiple upright stems from a central stool, typically reaching 6–15 feet in height with an open, vase-like form. Stems carry distinctive smooth, glandular-hairy young bark that ages to gray-brown. Periodic coppicing — cutting stems close to the base in a rotation — stimulates vigorous regrowth and is the traditional management style for both nut production and structural wood harvest.

• Leaves

  Leaves are broadly rounded with a doubly serrated margin and a slightly rough texture, emerging after the catkins fade in spring. Yellowing or browning leaf edges in summer often indicate drought stress or potassium deficiency; powdery mildew can appear on leaves in humid, crowded conditions but rarely affects nut production significantly.

• Flowers

  Hazelnut is monoecious, carrying both sexes on the same plant but flowering in a dissociated sequence that largely prevents self-fertilization. Long, pendulous yellow male catkins open in late winter — often February or March in temperate zones — releasing wind-carried pollen. Female flowers are tiny, bright red, and spider-like, emerging from separate buds on the same stems days to weeks later. A second genetically distinct plant within roughly 50 feet is needed for reliable pollination and nut set.

• Fruit

  Each nut is enclosed in a leafy, involucre husk that turns from green to papery brown as the nut matures. Nuts are ready to harvest when the husk begins to loosen and the nuts fall naturally or release easily when the branches are shaken. Nuts left on the ground are quickly taken by squirrels and jays; spreading tarps or netting beneath the shrub at harvest time recovers the crop efficiently. Freshly harvested nuts should be cured in a single layer in a cool, airy location for 1–2 weeks before storage.

Known Varieties

Common cultivars worth knowing

• Jefferson

  An Oregon State University release bred specifically for resistance to Eastern Filbert Blight, the most serious disease threat to hazelnuts in North America. Produces large, high-quality nuts on a vigorous shrub and is the leading commercial and home-garden variety for the Pacific Northwest.

  Best for: Pacific Northwest gardens and any region where Eastern Filbert Blight is established

• Wepster

  Another OSU blight-resistant release with excellent nut flavor and reliable production; slightly earlier ripening than Jefferson and a good cross-pollinator when paired with it.

  Best for: Cross-pollination partner for Jefferson in blight-endemic regions

• Barcelona

  The traditional commercial hazelnut of the Pacific Northwest, producing large, round nuts with excellent flavor; highly susceptible to Eastern Filbert Blight and best suited to gardens outside the blight range.

  Best for: High nut quality where blight is not present

• Corylus americana (American Hazelnut)

  The native North American species, smaller-nutted than European selections but exceptionally cold-hardy and naturally resistant to Eastern Filbert Blight. Valuable for food forest plantings, restoration hedgerows, and gardens in zones 4–5 where European varieties struggle.

  Best for: Cold-climate food forests, wildlife habitat, and blight-resistant hedgerows

• Eta and Theta (hybrid)

  OSU hybrid selections crossing Corylus avellana and Corylus cornuta for blight resistance combined with improved nut size over pure American hazelnut; suited to a wider geographic range than European-only selections.

  Best for: Upper Midwest and cold-zone growers seeking blight resistance with larger nut size