A filbert tree is actually a woody bushy plant that has been trained into the shape of a tree by pruning suckers at its base. It is a nut-bearing tree, producing the filbert nut. It is also known as a hazel; thus, another name for the filbert nut is hazel nut. The filbert nut tree is relatively small in size, growing from 15 feet (4.6 meters) to 20 feet (6.1 meters) at the maximum. Filbert nut trees need to cross pollinate to produce their nuts, and they typically like cooler, wet environments. About 75 percent of the commercial filbert nut crop comes from Europe, but they are also a commercially important crop of the Pacific Northwest in the United States.
Filbert plants can make excellent hedges when not pruned to form trees. They form suckers at their bases and spread into a bushy plant. The fact that this plant also produces a nut crop often makes its use appealing to home gardeners. Filberts also can attract birds and provide great cover for them. Blue jays in particular enjoy the nuts, and they often need to be deterred from eating the nut crop if it is being grown for commercial harvesting purposes.
Caution ought to be taken, however, when planting filberts in the United States because some varieties of the European Filbert tree are vulnerable to Eastern Filbert Blight, a fungal disease affecting the filbert's bark. The blight can be controlled by careful pruning, spraying, and replacing severely affected trees. Blight resistant varieties include the Turkish Filbert tree, the American Filbert tree, and many subspecies that have been developed through hybridization.
Filbert nut trees can be grown from seed, grafted or propagated by division. They actually flower in mid to late winter, with the nut being ready for harvest by late August to early September. The nut of the filbert tree varies in size depending on the variety planted, and it has many culinary uses. The filbert nut is often used in simple dishes featuring squash, sold in mixed nuts and cereals, and also in cookie and candy recipes.
The use of filberts as a food crop dates back to at least the time of the ancient Romans — Roman author and philosopher Pliny refers to them in his writings. At that time, however, they were not referred to as filberts. Instead, they were known as hazel nuts. The name filbert originated because the filbert nut was typically harvested in Europe around the Christian celebration of Saint Philbert's Day.