The hazels we sell are hybrids between Corylus avellana and Corylus americana. C. avellana takes a multi-stem form or can be pruned to a tree form and can reach 25 feet tall, with exceptional trees that can reach 35. C. americana is most often 8-12 feet, and is a suckering multi-stemmed shrub.

Climate

Hazelnuts prefer temperate climates with warm or hot summers and cold winters. Corylus avellana is found from coastal northern Europe, all across continental Europe down to the Mediterranean, and east to Turkey.

Topography and soil

Hazelnuts can inhabit fertile low lands and can handle poorer drier sites than many other productive nut species. They are able to thrive in calcerous and neutral soils, but generally are less amenable to acidic soils though they will grow on them. Hazelnuts need good drainage to a minimum of two feet of depth.

Ecological niche and stratification

Hazelnuts occupy a variety of different niches across their range. Where other larger trees can’t grow, hazelnuts can form the primary canopy as in the atlantic hazelwood of Scotland and Ireland. More commonly, mature hazelnuts in good production occupy a medium-high stratum. There are often widely spaced canopy trees above them, but the hazels will not be productive if completely shaded. Approximately half a day of direct sun is needed for good production. Hazelnuts thrive with a low stratum below of mixed woody and herbaceous plants. Bare soil or mown grass will have a detrimental effect on hazels because they form relationships with ectomycorrhiza, arbuscular mycorrhiza, and a wide range of basidiomycetes and other microorganisms many of which rely on the breakdown of woody material typical of forest soils.

The American hazelnut shares much of the above, but can tolerate more moisture and higher levels of acidity.

Pests & diseases

Eastern filbert blight is a fungal disease that reliably kills Corylus avellana without special management, hence the need for hybrids. There are few other significant problems, aside from squirrels taking the nuts when they become physiologically ripe. Squirrels harvesting is an indicator that the nuts can be harvested and dried.

Management

Hazelnuts do not need significant pruning for the first 2-3 years after planting. They can be left as a multi-stemmed shrub, or pruned to a single main trunk. After two years, they can be pruned similar to an open-center fruit tree with 3-4 permanent scaffold branches, or they can be left as a multi-stemmed shrub. Shrub forms benefit from the periodic thinning of shoots. Remove the oldest shoots once they have been producing nuts for several years but have begun to wane in production and allow new vigorous shoots to take their place.

It is an exciting possibility that, starting with hybrid hazelnuts, and planting them into a system with adequate canopy above them and forest community below, and receiving adequate management, we could circumvent eastern filbert blight and develop significant hazelnut production in many more regions of the country. Having harvested from C. avellana when in full production, I can say that it is a true joy to fill up 10 gallons of hazelnuts from a single bush. A whole winter’s worth of cracking can be picked up off the ground in 20 minutes.