Seeds from American Hazelnut Corylus american It is a medium to large shrub that under some conditions can take the form of a small tree. Grows up to 18 feet with 12 foot spread in zones 4 to 9. Requires two trees for pollination. American Hazelnut grows as a strong multi stemmed shrub, with edible nuts that mature in September to October. The nuts are edible, although smaller than the more commonly cultivated filberts such as Corylus maxima. It is planted by wildlife enthusiasts to attract and keep game in an area. Plant two trees for pollination.