Hazelnuts or Filberts

 By Kim Willis These articles are copyrighted and may not be copied or used without the permission of the author.

A new study by Oregon State University found that when older adults were given about a third cup of hazelnuts per day for 16 weeks it improved their blood levels of magnesium and vitamin E.  These two nutrients are often lacking in modern diets.  Other studies have found that people with low levels of these nutrients were at greater risk of developing Alzheimer’s disease. Did you know that most gardeners can grow these healthy nuts?

Some of you may know hazelnuts as filberts. Hazelnuts and filberts are essentially the same thing. The name depends on what country you are in and what species of Corylus you are growing.  There are native hazelnuts in both Europe (Corylus avellane, Corylus maxima) and North America (Corylus americana, Corylus cornuta).  There are also other species and hybrids of species.

Hazelnuts have alternate, heart shaped or oval leaves with toothed edges, (double serrate) that are paler green underneath and sometimes lightly hairy.  These nuts grow as small trees to about 15 feet or as shrubs depending on the conditions and pruning. Hazelnuts spread by suckering and soon form thickets of trees or shrubs. They are deciduous and fall color is variable, ranging from a dull yellow to pretty rose or purplish reds.

Male flowers are long yellowish drooping “catkins” that appear before the leaves.  Female flowers are small globes with red ‘petals” (stigmas) sticking out.  They also appear before the plant leaves. They are in clusters and a rough looking set of leaf bracts will surround them as they mature into nuts.

Each hazelnut plant has both separate male and female types of flowers but flowers on the same plant cannot mate in European hazelnuts and while you may get some nuts from a single American hazelnut, production is greatly improved with two or more plants. They are wind pollinated. For best production plant at least two hazelnuts.

The seed (nut) has a tough leaf bract, a thin hard shell, and a papery husk before you get to the part we call the nut meat. (Leave the shell on if you are planting a nut.)  It takes 7-8 months to mature on the tree and then the nuts fall.  Harvest is done by picking up the nuts after they fall.

Hazelnuts are cold hardy to at least zone 4 but nut production is often diminished from late frosts in zone 4-5. They will grow in most types of well drained soil and prefer full sun. In the south they tolerate partial shade but don’t produce as well in those conditions.

Gardeners may want to buy small trees to start a hazel nut grove. If you plant 3 feet tall trees, you’ll probably get a harvest in about 3 years.  It takes about 8 years to a harvest from planting a seed.  Buy domesticated cultivars if you want nuts for personal use as the domestic cultivars have larger nuts and a more abundant harvest. If you want them for wildlife, you can plant wild types.

Since hazelnuts sucker and produce a dense thicket if left alone you should prune out suckers too close to each other, leaving at least 6 feet between plants. Or if you want neat, tree shaped plants remove all suckers. You can prune hazelnuts so they form a shrub, to make them easier to harvest, by pruning down the leader or main stem by about a third.  Prune when dormant to shape the plant but you can take out suckers at any time.

Hazelnuts mature over an extended time period and will be ripe up to a month before they fall from the tree. Ripening may begin in September.  It’s easier to wait until they fall to harvest them, because you will know they are ripe then. You can give the trees a shake to speed things along.  Mow the area under the trees short when they start falling so you can see them.  Pick them up daily or animals will get them. The nuts may have fallen without the papery bracts or you can remove the bracts from nuts.

After you pick them up spread them out on newspaper in a warm, dry place for about two weeks.   A ripe nut has a firm, cream colored meat.  Nuts in the shell will last several months.  If you remove the nut meats store them in closed containers in a cool place.  Freeze them if you will be keeping them more than a month.

Hazelnuts are prone to blight diseases and some areas have problems with one strain of blight while others have problems with another. Look for blight resistant varieties grown locally. Dorris, Jefferson and Felix are some blight resistant varieties. Many animals and birds like the huts and you will have to compete with critters to get them.

Two types of worms, the filbertworm and the nut weevil, can infect hazelnuts.  This will leave tunnels in nut meats, or you may see small worms.  These will need to be controlled by insecticides.  Talk to your local Extension office to see what to use and when to apply it.

The countries that produce the most hazelnuts are Turkey, Italy and the United States in that order.  Hazel nuts can be eaten raw or roasted, made into a paste or “butter” and an oil can be expressed from them. They are often combined with chocolate in desserts called truffles, used in cakes, made into the spread called Nutella and a liqueur called Frangelico. 

There is an effort by the Arbor Day Foundation to locate wild North American hazelnuts so that genetic diversity can be preserved. If you know where some are growing you can contact them at;  https://www.arborday.org/programs/hazelnuts/consortium/locate.cfm

More reading

www.sciencedaily.com/releases/2018/12/181206135653.htm

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