Hazelnut Tree

Hazelnut trees, also known as filberts, are multi-stemmed, shrubby trees reaching 12 to 20 feet tall. They thrive in moderate climates with cool, moist winters and mild summers, similar to the Pacific Northwest or maritime Europe. Plant in full sun to partial shade in well-drained soil with a pH of 6.0 to 7.0. Hazelnuts tolerate more shade than any other nut tree but produce best crops in full sun. Space trees 15 to 20 feet apart.

Hazelnuts are wind-pollinated and require cross-pollination from a compatible variety that sheds pollen at the same time. This timing is critical because hazelnuts bloom in late winter, with male catkins releasing pollen in January and February when the tiny red female flowers are receptive. Plant at least two different varieties within 50 feet of each other. Water regularly during the first 2 to 3 years, then reduce to supplemental irrigation during dry periods.

Hazelnuts naturally grow as multi-stemmed bushes but can be trained to a single trunk or small tree form. If growing as a bush, allow 3 to 5 main stems and remove suckers growing from the base to prevent the planting from becoming an impenetrable thicket. Prune in late winter to remove dead wood, thin the interior for air circulation, and maintain shape. Begin harvesting nuts at 3 to 4 years of age, with full production reached at about 8 years. Annual yields of 10 to 25 pounds per bush are typical.

The common hazelnut (Corylus avellana) is native to Europe and western Asia, where it has grown wild since the end of the last Ice Age roughly 10,000 years ago. As glaciers retreated northward, hazel was among the first pioneering tree species to colonize the newly exposed landscape, forming dense thickets across much of temperate Europe long before larger forest trees could establish. Archaeological evidence from Mesolithic sites in Britain, Ireland, and Scandinavia shows that early human communities gathered and processed hazelnuts on an enormous scale, roasting them in pits and storing them as a critical winter food source. The Romans cultivated hazelnuts extensively and are credited with spreading improved varieties across their empire, referring to the nut as 'nux avellana' after the town of Avella in the Campania region of Italy where superior cultivars were grown. During the Middle Ages, hazel coppice woodlands were managed as a renewable resource across northern Europe, providing not only nuts but also straight poles for fencing, hurdles, thatching spars, and charcoal production. The hazelnut arrived in North America with European settlers in the 17th century, though a native species, Corylus americana, already grew wild across the eastern half of the continent. Modern commercial hazelnut production is dominated by Turkey, followed by Italy, Azerbaijan, and the United States, where Oregon's Willamette Valley produces over 99 percent of the American crop. Breeding programs in Oregon and elsewhere have developed blight-resistant cultivars that have transformed the industry and allowed hazelnut orchards to expand into regions previously unsuitable due to Eastern Filbert Blight disease.

Hazelnuts prefer well-drained loamy soil with a pH of 6.0 to 7.0. They tolerate a wider range of conditions than most nut trees but struggle in heavy, waterlogged clay or extremely sandy soil. Apply a balanced fertilizer in early spring, using about one-quarter pound of actual nitrogen per year of tree age. Boron deficiency causes blank nuts and reduced kernel development; apply borax at one ounce per tree annually if deficiency is suspected. Avoid excessive nitrogen that promotes vegetative growth over nut production.

Hazelnuts mature in September and October, indicated by the husks turning brown and the nut separating easily from the husk. Allow nuts to fall naturally or shake branches to dislodge ripe clusters. Collect from the ground daily to prevent moisture damage and squirrel theft. Remove husks and dry the nuts in a warm, well-ventilated area for 2 to 4 weeks until the kernel snaps cleanly when broken. Properly dried hazelnuts rattle in the shell when shaken.

Dried in-shell hazelnuts store at room temperature for 3 to 4 months and in the refrigerator for up to a year. Shelled kernels keep best in the freezer in airtight containers for up to 2 years. Roasting brings out the characteristic hazelnut flavor and makes the thin brown skin easier to rub off. Hazelnuts are outstanding ground into flour, made into hazelnut butter, or combined with chocolate in spreads and confections. Hazelnut oil is a prized culinary oil for salad dressings and finishing dishes.

Hazelnuts have a distinctively rich, sweet flavor that makes them one of the most prized culinary nuts worldwide. The classic combination of hazelnut and chocolate is showcased in spreads, truffles, and pastries. Hazelnut flour adds richness to cakes, cookies, and macarons. Toasted hazelnuts are excellent in salads, pasta dishes, and grain bowls. Hazelnut oil is a premium finishing oil. Frangelico and other hazelnut liqueurs are popular in desserts and cocktails.