Theta Filbert HazelnutConveniently Sized Hazelnut Can Produce in 1 Year Why Theta Filbert Hazelnut Trees? It's a classic tree, now grown for optimal benefits. Not only can it produce fruit in its first season, under optimal conditions, but it's also carefree. What else makes the Theta Filbert a must have? It's a beautiful tree with large, thick green leaves. It's resistant to pests and diseases, including Eastern Filbert Blight and tolerant of heat and humidity. And it's