Prohibited to AZ
(Corylus species) Filberts are easy to grow and very productive! Filberts can be grown in USDA Zones 5-9. They are by far the most important nut crop grown commercially in the Pacific Northwest. This small tree prefers a cool, wet climate. Filberts flower in mid-winter. The abundant male catkins make a showy display. Humid, windy weather is ideal for distributing pollen to the tiny red female flowers. By the end of August nuts are ripe. They drop in September.