Lois Braun, University of Minnesota Research Fellow
When I tell people that I am a hazelnut researcher in the Department of Agronomy at the University of Minnesota, they invariably respond in one of two ways. They may say, “Oh! I didn’t know that hazelnuts grew in Minnesota!” Or they may say, “We used to pick wild hazelnuts in the woods when I was a kid—but we didn’t usually get very many because the squirrels got them all.”
More on squirrels later.
People are right that European hazelnuts, Corylus avellana, the ones that produce those big round nuts you find in party nut mixes, don’t grow in Minnesota. They’re not winter hardy here, at least not the domesticated varieties, which come from the Mediterranean region of Europe. In this country they’re grown in the Pacific Northwest, mostly in Oregon.
Photo 1: Nut cluster. Lois Braun
But there are two wild species of hazelnuts that are hardy in Minnesota. The American hazelnut (Corylus americana) is widespread in the Eastern half of the United States, whereas the beaked hazelnut (Corylus cornuta) is found further north into Canada. Both species are shrubs found in the understory of the savannah or in open woods, often near the margins of wetlands. Their nuts are borne in clusters and enclosed in papery green husks. The beaked hazelnuts get their name from the beak or snout shape of this husk. The nuts of the wild species are tiny—only about the size of a pea, as compared to the size of a spherical dime for European hazelnuts. But they’re packed full of flavor, or so I’m told, since I’ve never actually tasted one… because of those dang squirrels.
Hazelnuts have a unique reproductive strategy. Like other members of the birch family, they produce their male flowers, catkins, in the fall. Catkins dangle from the branches all winter before expanding and releasing their pollen in the very early spring. (I once visited Itasca State Park in April when the hazelnuts were in bloom. I wouldn’t have noticed them at all if it had not been for all the yellow catkins at a time of year when the lakes were still frozen and the rest of the plant world still appeared asleep.) The female flowers, which don’t emerge until spring, are exceedingly inconspicuous. They look like a pin-head sized tuft of red on the tip of a leaf bud. What’s unique about them is that after pollination in April the pollen germinates and grows a pollen tube down the style and then…nothing happens for another two months! The pollen and the ovule do not fuse to form a new embryo until June, but after that the nut expands rapidly and is mature by late August or early September. The early flowering appears to be a strategy to take advantage of the optimal conditions for wind pollination in the early spring, when there are no leaves to get in the way of blowing pollen. The delay in formation of a new embryo may be because it isn’t until June that conditions become optimal for growing the nuts.
Photo 2: Hazelnut catkin. Lois Braun
The hazelnuts I am working on are hybrids between the European hazelnuts and these two native American species. The American species confer hardiness to Minnesota’s harsh winters, and tolerance to a disease that would kill European hazelnuts if we planted them here, while genes from the European hazelnuts increase the nut size. Unlike squirrels, we humans don’t have all day to shell out enough nuts to get a proper meal out of small nuts. We don’t have the teeth of a squirrel either.
Photo 3: One year old planting. Lois Braun
Why, you are probably wondering, am I researching hazelnuts in the Department of Agronomy? Isn’t agronomy about growing field crops? Yes. We’re interested in developing hazelnuts as an alternative crop for Minnesota, to add diversity to an agricultural landscape dominated by corn and soybeans.
There are multiple benefits to woody perennial crops such as hazelnuts. They require no tillage once they are established, and require much lower inputs for weed control and fertility than crops such as corn and soybeans. This reduces soil erosion and the potential for contamination of surface and ground water by herbicides, fertilizers and sediment. Low inputs also keep production costs low. Because hazelnuts are ideally suited for planting on steep slopes, in riparian zones, and other places that are inappropriate for annual tillage, they offer growers a way of making a profit from land that would otherwise be idle, at the same time maintaining or enhancing the ecological value of this land. They can be used in windbreaks, to reduce winter heating costs around a homestead; as shelterbelts, to protect livestock or crops from strong winds; as living snowfences, to reduce drifting snow along highways; or to protect sensitive lake and river shores, all while generating income for growers. We recommend planting low-growing perennial mixes of grasses and legumes between the hazelnut rows, which further enhances their value for stopping erosion, building soil organic matter, and supporting a complex and resilient ecosystem. Finally, they make great wildlife habitat, and the nuts are loved by a wide range of animals—especially squirrels.
Photo 4: Living windbreak of hazelnuts. Lois Braun
We believe that we will have no trouble marketing hazelnuts because the nuts are tasty and nutritious. They are high in protein, healthy mono-unsaturated fatty acids, and Vitamins B and E. They can be eaten straight, baked into cookies, sprinkled on salads, or ground into a peanut-butter like sandwich spread. The oil has properties virtually identical to olive oil, for use in cooking and in lotions. Some people are even talking about using it to make biodiesel fuel.
Photo 5: Hazelnuts laden with nuts. Lois Braun
So what’s the down side? Right now, the hybrid hazelnuts you can buy from a nursery are all seed-propagated. You probably know that you can’t take the seeds out of a Honeycrisp apple, plant them and get a Honeycrisp apple tree. They won’t come “true”. The way to get a new Honeycrisp tree is by grafting from another Honeycrisp. It’s the same with hybrid hazelnuts, except that you can’t graft hazelnuts because they’re multi-stemmed bushes. New shoots would keep coming up from the rootstock and overwhelm the grafted shoot.
The problem with planting seedlings is that you don’t know what you’ll be getting, even if the seeds came off a spectacular bush. Some may be as good as the mother plant, some may be better, but most will not. They’ll be as diverse as a litter of stray kittens. It is very difficult for a commercial grower to manage a crop in which plants that are three feet tall are right next to ones that are ten feet tall, or in which some nuts mature in mid-August and others in mid-September.
The objective of my research is to find methods of propagating hazelnuts vegetatively so that growers can count on a consistent crop. So far, mound layering has proven to be the best method, but it can only produce a few new plants from each parent plant, and is hard work. Hazelnut stem cuttings don’t root well, and tissue culture is expensive, at least to start. So I keep looking for better methods. Someday in the not-too distant future I hope that we can offer Minnesota growers, and homeowners, a reliable new crop.
Photo 6: The author inspecting a tall growing hazelnut.
But diversity isn’t always a problem. A home-owner picking hazelnuts for personal consumption might prefer a spread-out harvest. So if you are adventurous and don’t mind a little uncertainty, how about planting a couple of open-pollinated hazelnut seedlings in your yard. Here are some nurseries in our region that sell them:
Red Fern Farm
13882 I Ave.
Wapello, IA 52653
Badgersett Research Corporation
18606 Deer Road
Canton, MN 55922
New Forest Farm
P.O. Box 24,
Viola, WI 54664
E-mail for a price list: firstname.lastname@example.org
Seedlings come as small “tubelings”, which are actively growing, or as larger bare-root dormant seedlings. Seedlings grown a little longer in larger containers usually have better survival, but are more expensive. Some growers have found that they can increase the survival of the small tubelings by transplanting them into larger pots in June, keeping them in a nursery setting over the summer, then transplanting them outdoors in August or early September.
Photo 7: A little extra care is needed during the first year or two of establishment. Lois Braun
Detailed advice on growing them is available at http://www.extension.umn.edu/Agroforestry/components/hybrid-hazelnuts.pdf
Although hazelnuts need a fair amount of attention during the first year or two, once they are established they require very little care. They do best on rich high organic matter soils, but can be grown on poor soils. Just be sure to test the soil and correct any deficiencies first. Nitrogen requirements are very low for the first few years and can easily be supplied from the soil or from compost. Composted manure may be all that is necessary to keep them productive once they start bearing nuts. Weed control, watering, and protection from wildlife are important during the establishment phase. If you have only a few it is easy to weed and water them by hand. Mulching reduces the need for both of these. By the third year, hazelnut roots should be deep enough that they can compete against weeds on their own pretty well. After this they should only need watering if it’s exceptionally dry or if they are on sandy or other droughty soils. Chicken wire cages are effective protection from wildlife, and can be removed after two winters.
Bushes will start producing in about their fourth year, but don’t reach full productivity until about year eight. At that time your biggest challenge will be getting to the nuts before the squirrels do! But if you don’t, take pleasure in having done your part to keep Minnesota’s wildlife well fed!