One of my favorite trees is Henry Lauder’s Walking Stick or Contorted Filbert (Corylus avellane ‘Contorta’). I love its unusual, gnarled appearance with its crazy cork-screwed branches. It shares the genus Corylus with 2 native relatives living in North America: the American hazelnut (Corylus americana) and beaked hazel (Corylus cornuta). This group of trees is called hazels or filberts (genus Corylus) and is comprised of about 12 species of trees and shrubs worldwide.
Corylus is one of 5 genera of deciduous trees of the Betulaceae family or birch family in North America. The other four genera in the Betulaceae are Alders (Alnus), Hornbeams (Carpinus), Hophornbeams (Ostrya), and Birch (Betula). There is no known Champion tree for this species.
The American hazelnut is usually found as a small colony-forming, rounded, multi-stemmed shrub, but sometimes it appears as a small, single-trunked tree. They grow to 8 to 10 feet in height on average with a spread of up to 15 feet. These deciduous plants are moderately long lived. Their leaves are single with doubly serrate margins and are broad-ovate to broad-elliptical or heart-shaped in general terms. The leaves usually measure 2.5” to 6” long by 1.5” to 2.5” wide and are dark green in the summer turning to an unattractive mottled yellow green in the fall. Leaves are alternately arranged with short ½” hairy petioles. Hazelnuts are multi-stemmed with dense ascending branches. Twigs are dark brownish-grey and hairy.
Hazelnut flowers bloom in late winter to early spring long before their leaves appear. Both male and female flowers are catkins. The male catkins are 1.5” to 3” long, drooping green to yellowish-brown inflorescences on short brown stalks. The female flowers are tiny and inconspicuous, carmine-red, sea urchin-shaped catkins.
The fruit is an edible nut. The nut is borne in a husk of modified leaves called an involucre. The 1” fused husk is pubescent and deeply toothed. These involucres can appear singularly or in clusters with up to 12 in a cluster. The rounded ½” nuts have brown shells with a slightly flattened side. Their shells are thicker and harder than the commercially grown varieties of hazelnut. The white to beige kernel or seed inside is deeply lobed.
The outer bark of the American hazelnut is light grey to light copper brown. The outer bark exfoliates on mature specimens revealing the yellow to light orange inner bark.
Hazelnuts do not have a deep taproot like most nut trees. Their roots are shallower and more fibrous, which make them easier to transplant.
The four best identifying factors of the American Hazelnut are:
- America hazelnuts usually grow in clumps as rounded shrubs.
- They have heart-shaped serrated leaves.
- Their leaves and twigs have a wintergreen scent when crushed.
- In winter, they can be easily identified by their long, yellowish-brown catkins dangling from their branches.
Habitat /Zone /Range
American hazelnuts are usually found growing at the edges of woodlands or wetlands, along fence rows, as an understory tree in forests, in uplands, valleys, and prairies. They prefer stony, coarse, well-drained, loamy soil on hillsides. They stretch from Zone 2 through Zone 9, but flourish in Zones 5 to 8. They are found growing in an expansive range from Saskatchewan eastward to Maine, southward to Georgia, westward across the Southeast to Oklahoma, and northward to North Dakota.
Hazelnuts are a relatively low maintenance, easy crop to grow. They thrive in full sun, but will tolerate deep shade. Nut production is directly tied to the amount of sun they receive, so try to pick a sunny location for good nut production. These trees are adaptable, tolerating many soil types and pH levels, but they prefer a light, loamy soil with a pH of 6.5.
Plant in fall or early spring. Space the plants 3 to 5 feet apart if forming a hedge or 15 to 20 feet apart if starting an orchard.
Irrigation & Fertilization
Mature hazels rarely need to be watered. Only during times of drought or in the extreme heat of summer will hazelnuts need some irrigation. Water at a rate of 1” per week when irrigation is required.
High nitrogen fertilizers should be avoided, and instead organic composts or mulches should be used to fertilize hazelnut trees. Nut production can be reduced if these plants are kept too lush with high nitrogen inorganic fertilizers. Thus, low nitrogen organic fertilizers like mushroom compost, manures, and fish emulsions will supply enough nutrition for your trees. Only if your trees are growing at less than 6” per year and exhibiting yellowed or small leaves, will it be necessary to apply a small amount of commercial fertilizer. Do not apply any kind of fertilizer after mid-August or it will make your trees more susceptible to cold damage.
Pruning & Training
American hazels want to grow naturally as thicket forming large shrubs. You will have two form options either as a large shrub or as a small tree. Of course, the tree form option will take a little more effort.
To train your hazel into a vase-shaped, multi-stemmed, small tree, prune the young plant to a single trunk with 3 to 6 main branches when it is three years old. Dig up and remove root suckers on a regular basis to maintain a thicket-free area around the base of tree, this will also make it easier to harvest the nuts each year. Regularly remove diseased or damaged branches through the year as the tree grows.
For a shrub form, initially prune the plant to 3 main trunks when it is 3 years old. Then, cut out cross branches and older wood each winter to stimulate new growth. This open form allows more sun to penetrate the center of the canopy, which will over time cause the tree to produce more nuts.
American hazelnuts are monoecious, which means both male and female flowers develop on the same tree and many times on the same branch. Hazelnuts are partially self-fertile to fully self-fertile and are wind pollinated. To have dependable pollination and good nut production it is best to plant 2 to 5 trees. If you choose to use another variety of hazelnut or filbert as a co-pollinator, be careful that the two varieties are compatible and bloom at the same time.
There are several methods to propagate hazelnuts such as cuttings, grafting, layering, and tissue culture, but the best method of propagation for the American hazelnut is by seed.
Propagating hazelnuts by seed can take two different forms. Seeds can be planted outdoors in 1-gallon pots in the fall or held indoors in a refrigerator for 3 to 6 months to accomplish cold stratification. First, gather the nuts in September as the husks begin to turn brown. Dry the nuts indoor until the husks begin to open. Remove the shriveled husks and drop the nuts into a bucket of water to test for any bad seed. The diseased or non-viable nuts (seeds) will float.
You can select 1 of 2 seed propagation options. The nuts can be planted immediately into 1-gallon pots of sterilized seedling potting mix and left outdoors all winter to naturally go through cold stratification or held indoors for artificial stratification. Both options will benefit from making a small hole in the top side of each nutshell with a fine-toothed file, this practice is called scarification and will promote the germination process.
In the other seed option, dry the nuts and place them in a paper bag. Keep the nuts in a refrigerator set at 40-degrees Fahrenheit till at least November. Soak the seeds in water for 4 days to rehydrate them, then place the seeds into a closed container of moist sand. Put them back in the refrigerator. In February, take the container of sand and seeds back out of the refrigerator. Check the seeds each day for the next 10 days, each day, removing the newly germinated seeds. Plant each sprouted seed 1 to 2 inches deep in a 1-gallon pot of a sterilized seedling potting mix. Repot your tree seedling again in 6 months into 3-gallon pots and field-plant the young trees the following spring.
When using cuttings as the method of propagation, the cutting should be taken in late May to early June when the tree is actively growing. Select tip cutting, 4-to 6-inches long and up, half the diameter of a pencil with 1 to 2 leaves present. Dip the cuttings into a 1,000 to 2,000 ppm solution of indole butyric acid (IBA) and stick them in a seedling flat of pure perlite or a well-drained seedling mix. Give the cuttings bottom heat of 70- to 72-degrees Fahrenheit. Mist them evenly on a regular basis, but do not over water them. Overwatering can cause rot and decline. The cutting should be rooted in 4 to 6 weeks. Harden them off in a shaded area outside, then plant up the young trees into 1-gallon pots.
Simple layering is another good way to propagate hazelnuts. This can be accomplished by taking a flexible lower branch and scratching off the bark on the lower side about 10 to 12 inches from the tip. Take a shepherd’s hook tent stake or landscape staple and clip the section with exposed bark into the ground. Cover with 2 to 3 inches of soil and leave 6 to 9 inches of the tip exposed. It may take a season or two before the layered cutting develops roots and can be detached from the parent tree, then plant the layered section into a 1-gallon pot. These young trees can be shifted up into larger pots or field planted the next growing season.
Grafting is another method of propagating hazelnuts. Cleft-grafting and budding have both been successful, but budded plants seem to have more vigor than grafted plants. American hazelnuts are sometimes used as the rootstock of commercial hazelnut varieties.
Little research has been done on the micropropagation or tissue culture of native hazelnuts.
Pests & Disease
Like many fruit and nut trees, hazelnuts are attacked by many pests and diseases. But, being such resilient trees, few are ever serious enough to damage nut crops or kill the tree. Pests such as aphids, weevils, mites, Japanese leaf hoppers, bagworms, filbert worms, caterpillars, and scale insects can present a threat to hazelnut trees. Most of these pests can be managed by spraying dormant oil or fruit tree spray twice a year. Also, it is a good practice to rake up nuts left on the ground at the end of each fall to limit worms and weevils the next year. Many creatures such as squirrels, chipmunks, turkeys, and other birds can consume your hazelnut crop.
A host of diseases from bacterial to fungus and viral can infect your hazelnuts. Bacterial leafspots, blights, crown galls, cankers, and fungal leafspots like anthracnose, powdery mildew, rusts, and viral hazelnut mosaic can pose problems, most are just nuisances. The most concerning malady for hazelnuts is root rot.
Extended periods of saturated soil after heavy rains can cause wet feet or root rot in hazelnuts. Full sun in the heat of summer can cause sun scald damage especially on younger plants. Catkin blast or deformed catkins and empty nuts shells (blanks) can occur, neither of which have a conclusive cause.
Harvest & Storage
Most American hazelnuts start producing nuts when 2 to 3 years old, but may be 10 years old before reaching maturity. The nuts ripen in September and October. The trees normally bare heavier in alternate years. A mature tree will produce 20 pounds of nuts per year on average.
The nuts are ready to harvest when the husks turn yellow and the nuts can be easily pushed around in the husks to free them. It is best to pick the nuts before they fall to the ground and are lost to wildlife. The nuts may be picked by hand or a padded stick can be used to shake them from the branches. With either method, an old sheet or tarp can be placed under the trees to catch the nuts.
The nuts need to be fully ripe and dried to store properly. The nuts may be dried outside spread out on newspaper in the sun for 7 to 10 days or dried indoors for 14 to 21 days. A food dehydrator can also be used. If you choose to dry them outdoors, be sure to cover them with wire screens to protect the nuts from marauding squirrels. The nuts are sufficiently dried once the kernels become crunchy. The kernels can be stored in or out of their shells. They will store for up to a year in a cool dark place or for a couple years if packed in salt.
Even though American hazelnuts are not as large as European filberts, they make up for it with a milder, sweeter flavor than commercially grown varieties. They can be eaten raw or roasted by the handful and used in numerous ways in cooking and baking. Chopped hazelnuts can be used as a savory topping on salads or to add an extra punch to deserts such as ice cream and cakes.
A flour made from grinding the nuts can be utilized as a basic ingredient in cakes instead of wheat flour. Nut butter can be made and used in spreads for toast or in frostings for cakes. Gourmet pasta sauces sometimes employ hazelnuts because their flavor pairs well with lemon and spinach. An edible oil made from crushed hazelnuts is used in salad dressings or as an ingredient in cooking. Chocolate coated or sugar and cinnamon covered hazelnuts make great party snacks.
Hazelnut wood is a preferred wood to use for smoking cheeses and meats.
Nutritional Benefits & Medicinal Uses
Hazelnuts are full of minerals, vitamins, protein, antioxidants, healthy fats, and dietary fiber. These nutrient dense nuts are rich in numerous minerals such as, iron, potassium, copper, magnesium, manganese, selenium, zinc, and calcium. They are also a good source of B-complex vitamins and vitamin E. These protein rich nuts are useful in building muscle. The nuts are 50% to 70% oil, which contain many healthy fatty acids and carbohydrates so they should be eaten in moderation. The dietary fiber found in hazelnuts helps prevent constipation and possibly assists in lowering the risk of some forms of cancer.
Hazelnuts are good inflammation fighters because they contain high levels of vitamin E and other antioxidants. These nuts are especially useful in combating inflammation in the cardiovascular and nervous system. The monosaturated fatty acids contained in hazelnuts help reduce inflammation in the heart and circulatory system promoting heart health and reducing the risk of heart attack. Consuming hazelnuts can also assist in lowering bad LDL cholesterol in the blood. The same antioxidants and vitamin E are also helpful in protecting against disease by boosting the immune system. These antioxidants also protect the body from sun damage thus improving the quality of hair and skin. Hazelnut oil, which is high in vitamin E, is also an excellent moisturizer for the skin and keeps the skin supple.
Hazelnuts make a great snack for diabetics since they aid in regulating blood pressure and lower blood sugar levels. Regular consumption of hazelnuts can also have a calming effect on the mind and improve short-term memory. These nuts may also slow the aging of the brain.
Eating hazelnuts in moderation can also assist in weight loss and weight management by boosting the metabolism. The thiamin and folate in these nuts are especially helpful in promoting healthy metabolism.
Native American Uses
The American hazelnut tree was used for fiber, medicine, and food by many tribes. Many tribes used the straight root suckers for fish net hoops and arrow shafts. The Ojibwa and Meswaki utilized the twigs and branches to make baskets, brooms, brushes, and drumsticks.
Hazels were an important medicinal for many native peoples. The Iroquois formulated a decoction of hazelnut roots to treat toothaches. The Chippewa made an analgesic preparation by mixing hazelnut bark with charcoal. Skin medications for hives, cuts, and abrasions were made from the inner bark of hazels by the Cherokee, Iroquois, and Ojibwa. The Cherokee and Iroquois also created a bark decoction as a remedy for summer sickness or stomach viruses.
Many tribes gathered hazelnuts for fresh eating. The Menominee produced a nut milk, and the Dakota made a nut soup from hazelnuts. The Cherokee and Iroquois boiled or mashed nutmeats to save for winter and baked hazelnuts in breads.
Other uses for hazelnuts were also found. The Ojibwa mixed hazelnuts and butternut hulls to produce a dark black dye. The Iroquois, who had so many uses for hazelnuts, compounded bear grease and hazelnut oil together to make a mosquito repellant, as well as a hair tonic.
Hazelnuts are best used at the edges of your property in informal or naturalized areas where they can spread as an understory tree/shrub. Hazels can also be utilized as a screen at the back of shrub borders or as a hedgerow or windbreak. But in most cases, they are too large and ungainly to be drawn into most contemporary landscapes.
The nuts, foliage, as well as catkins of the American hazelnut are a good food source for wildlife such as deer, turkeys, squirrels, chipmunks, woodpeckers, and rabbits. Turkey especially like to nibble on the catkins as a winter treat. The foliage has been used as livestock fodder since the times of the settlers. Settlers also used the hazelnut stems to make wattle and daub constructed walls on their frontier houses. Basket weavers have utilized the strong, flexible branches for basketwork for centuries. The pliable branches are also used for fencing. Dousers use the forked branches to make divining rods to source water.
There has been little research into new varieties of the American Hazelnut since the nuts are small and considered inferior to commercially grown varieties. But, there is one hybridized variety, Corylus americana ‘Winkler’, which is a fully self-fertile cultivar that produces larger nuts and is more productive than most native types.
Hazards & Cautions
Because of their small size, hazelnuts pose a choking hazard to small children. Hazelnut pollen can also trigger hay fever (allergic rhinitis) in some sensitive people. But, the most dangerous hazard is to people with nut allergies. These allergies can range from being as mild as causing coughs or swollen eyes to respiratory arrest and death.
The American hazelnut, although smaller than the commercially grown hazelnut varieties, has a sweeter and more intense flavor than its well-known relatives. Having many health benefits and outstanding flavor, this little known native also has potential to become a commercially successful variety. In the meantime, it is great for foraging for those in the know. So, go out in a forest near you and mark or GPS plot some local trees. They will be the easiest to find in the late winter or early spring with their long dangling catkins. This way you will be ready for the harvest next fall. Or, add a few to a naturalized area in your landscape or add them to your own food forest.
References & Related Links
- Biggs, Matthew; McVicar, Jekka; and Flowerdew, Bob. Vegetables, Herbs, and Fruit: An Illustrated Encyclopedia. Buffalo, New York: Firefly Books, 2013.
- Creasy, Rosalind. Edible Landscaping. San Francisco: Sierra Club Books, 2010.
- Dirr, Michael A. Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation, and Uses. Champaign, IL: Stipes Publishing Co.,1990.
- Dirr, Michael A. and Heuser, Charles W. The Reference Manual of Woody Plant Propagation: From Seed to Tissue Culture. Athens, GA: Varsity Press, 1987.
- Hageneder, Fred. The Meaning of Trees. San Francisco: Chronicle Books, 2005.
- Kirkman, L. Katherine; Brown, Claude L.; Leopold, Donald J. Native Trees of the Southeast: An Identification Guide. Portland: Timber Press, 2007.
- McClure, Susan and Reich, Lee. Rodale’s Successful Organic Gardening: Fruits and Berries. Emmaus, PA: Rodale Press, 1996.
- Mellicamp, Larry. Native Plants of the Southeast. Portland: Timber Press, 2014.
- Moerman, Daniel E. Native American Ethnobotany. Portland: Timber Press, 1998.
- Russell, Tony and Cutler, Catherine. Trees: An Illustrated Identifier and Encyclopedia. London: Anness Publishing, 2004.
- Whittingham, Jo. Backyard Harvest: A Year-round Guide to Growing Fruits and Vegetables. New York: Dorling Kindersley Ltd., 2011.
- Viertel, Arthur, T. Trees, Shrubs, and Vines: A Pictorial Guide to the Ornamental Woody Plants of the Northern United States. Syracuse, New York: Syracuse University Press, 1970.
- Edible Landscaping – (434) 361-9134 361 Spirit Ridge Lane
www.ediblelandscaping.com Afton, VA 229020
- One Green World – (877) 353-4028 6469 SE 134th
www.onegreenworld.com Portland, OR 97236
- Rhora’s Nut Farm & Nursery – (905) 899-3508 33083 Wills Rd.
www.nuttrees.com Wainfleet ON LOS 1VO Canada
- Willis Orchard Company– (866) 586-6283 200 McCormick Rd. SW
www.willisorchard.com Cartersville, GA 30120
- Raintree Nursery – (800) 391-8892 Morton, WA 98356