University of Vermont Extension 
Department of Plant and Soil Science

 Fall News Article


NUT TREES FOR NORTHERN LANDSCAPES
 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
           
Along with pumpkins and gourds, you often find a selection of nuts in stores and farm markets in the fall.  If you like nuts such as black walnuts, butternuts, Chinese chestnuts, and hazelnuts, consider growing your own as their trees are hardy in northern regions.  They make great ornamental shade trees as well.  Nuts are a good source of proteins and other nutrients, feed wildlife, and require very few inputs of time and resources—much less than most fruit trees.

Although most nut trees eventually can 50 feet tall or more, hazelnuts only grow to about 15 feet or so.  You don’t have to wait until trees are mature for harvest, as most start bearing in only 4 to 5 years from planting small trees.  When mature, most may yield 60 to 75 pounds of nuts, with 20 to 25 pounds for hazelnuts.  Breeding over recent decades has resulted in some nut cultivars (cultivated varieties) that are hardier, bear earlier and with more nuts, and may be more tasty and easier to crack. 

If you’re sowing from seeds, fall is a good time, just as the squirrels do.  Make sure and cover with some screen or netting so squirrels and chipmunks don’t find them.  This marks where they are too, as they may not sprout until the following summer. Or you can sprinkle moth balls or a commercial repellent around them.  Buying small trees will get you a crop sooner. If you’re transplanting trees, spring is the best time and only for small trees, as they quickly develop deep tap roots making them hard to relocate. 

Most nut trees need at least two different cultivars, or just different plants if only a species, but they need to be of the same species.  Often wild species, if nearby, will pollinate a cultivar.  Plants should be within a hundred feet so the wind can blow the pollen between plants.

Choose a site with a deep (for the deep tap roots), well-drained soil.  Nut trees generally will tolerate a range of soil acidity or pH.   If growing from seeds, the first year seedling gets its nutrients from the seed, so there is no need to fertilize.  For small plants, or second year seedlings, fertilize in spring with a fertilizer rich in nitrogen.  Keep trees well-watered, as you would other trees, watering deeply once a week if no rain (more often on sandy soils).
 
Mulching around the trunk, but not up against it, will help control weeds and prevent mechanical damage to the trunk.  Place a tree guard around trunks of young trees to protect them from winter sunscald and mouse damage.  Stake trees for a couple years if they are in a windy location.  Raking leaves in the fall will help prevent diseases, although nut trees seldom get any.

Choose a site, too, with enough space for the tree to reach its mature size without interfering with buildings or other plants to the sides, utilities below ground, or overhead wires above them.  Don’t plant where shade will interfere with desired gardens, flower beds, or lawns.

Be aware that black walnut and butternut give off a toxic substance (juglone) to many other plants, preventing them from growing nearby.  This is called “allelopathy”, and was first noted on black walnuts by Pliny the Elder, a Roman natural science expert of the time, about 77 A.D.  Lawn grass, some annual flowers such as impatiens, and many herbaceous perennials are not affected by these trees, except perhaps by their shade.
 
Nut trees need little pruning, except to remove broken or diseased branches, or ones too low that interfere with mowing or other activities.  Too much pruning actually can delay fruiting.  You can prune to keep to a lower height, just make sure to keep a strong central trunk or “leader” in early years of small trees.  As the tree grows, remove branches that aren’t evenly spaced around the tree, and that aren’t about 18 inches apart from the others, measured vertically.  Also remove branches that are very upright, as those at wider angles from the trunk will be stronger as they grow and less likely to break in storms or winter.  Hazelnuts are an exception, being pruned more like a large shrub, with 5 to 7 main shoots. Prune out weaker ones, and ones in the center to allow light to enter.

You can rake up ripe nuts as they fall, or shake small trees or branches of larger ones so they drop the ripe nuts onto a tarp spread below.  If picking nuts, you may get ones unripe, which are very difficult to open.  Don’t allow nuts to remain on the ground, as they’ll decline and rot.  Lay them in a single layer on screens, or similar, to dry in a warm area with good air circulation such as attic or greenhouse benches,.  Periodically turn the nuts.  You can then store them in burlap bags or boxes, or shell and freeze.  Frozen, the nuts will store for several years. 

The black walnut eventually reaches 50 to 75 feet high, and 35 to 50 feet wide.  It shouldn’t be confused with the European or Persian walnut, the ones we usually find in stores.  In addition to the drawback of this native tree of allelopathy, its nuts have a smoky and strong flavor that not all like.  This tree has been used more for its timber than fruit.

Butternuts were a staple food of the Iroquois native peoples during northern winters.  This native tree is closely related to the black walnut, reaching a similar size, but with flavorful nuts.  Pour boiling water over them, let stand 15 minutes, then tap with a hammer to crack open.  Unfortunately, butternut blooms may be damaged by late spring frosts, and a disease has nearly eliminated them from natural stands in some areas. 

The hazelnut may be called an American filbert, as it is related to the European filbert which is slightly less hardy.  It has prickly burrs on the outside husk covering the nuts, making them a bit harder to handle.  Recent cultivars may have better fruit, and resistance to a blight disease.  Growing about 15 feet high and wide, it is good for smaller landscapes.

The Chinese chestnut is the one usually found for sale, as the chestnut blight of the early 1900’s wiped out most our native American ones (although there are some resistant cultivars you may now find).  It is often grown merely as an ornamental, with its long leaves and sweetly fragrant flowers.  It is a bit smaller than other nut trees, only reaching 40 to 60 feet high and 30 to 40 feet wide.  Some nuts can be eaten raw, but are usually roasted over a fire or heated in a microwave for about a minute.  Look for cultivars with some blight resistance.

There are other nut trees that will grow in warmer areas (USDA zones 5 and warmer), including filberts, hickories, pecans, and walnuts.  Almonds and pine nuts usually are grown in hotter or drier areas of the west.   If you want to learn much more about growing nuts, you may want to look into the North Nut Growers Association (www.nutgrowing.org).  There also is an excellent publication available online or to order from Cornell University on Nut Growing in the Northeast (www.gardening.cornell.edu/fruit/pdfs/nutpub.pdf).
 

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