Hazelnuts, or filberts, do best in areas with mild, moist winters and cool summers. About 99 percent of all the hazelnuts grown in the United States are grown in Oregon, mostly in the Willamette Valley. Hazelnuts start producing nuts when they’re around 4 years old, but they don’t become fully productive until they’re 7. Harvesting is usually done in October.
Hazelnuts ripen in September. Mow the ground around the hazelnut trees to clear it of grass and weeds before ripening begins. This will make harvesting easier, since it’ll allow you to rake the nuts into piles once they start to fall.
Hazelnuts should be harvested before autumn rains arrive. Nuts drop from the trees as they ripen, during a six-week period that usually starts in September. Once the nuts start dropping, shake the remaining nuts free from their branches with a pole. Early drops may be wormy or empty. You can tell the difference between good and bad hazelnuts by putting the nuts in water and removing the ones that float. Insect-infested nuts will have holes in the shells. They should be thrown out.
Start drying hazelnuts within 24 hours of harvesting. Place nuts in an onion sack, or on a tray with a screen bottom, so they receive good air circulation. Nuts will dry in two to four weeks, if placed in a warm, dry area and stirred every day. Using a food dryer set to a temperature of 90 to 105 degrees Fahrenheit will shorten the time to two to four days. Nuts can also be dried over a radiator or furnace, as long as the temperature stays below 105 degrees Fahrenheit. Shelling the nuts first will shorten the time, and you won’t have to use as much heat, either. As hazelnuts dry, the nutmeat turns spongy and creamy in color. Nuts are done drying when the centers turn creamy and the nutmeat becomes firm.
Hazelnuts can be stored at room temperature for several months, as long as they aren’t shelled. Shelled nuts should be used within a few weeks or stored in the refrigerator. If refrigerated or frozen, they will keep for one year. Large amounts of hazelnuts can be stored in sacks and kept in cold rooms that are between 15 and 20 degrees Fahrenheit. In addition, there should be no water pipes or other sources of moisture in the room.