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Grow your own Christmas chestnuts
December 28, 2005
CORVALLIS, Ore. - If you’ve ever dreamed of roasting chestnuts by an open fire, you might want to consider growing your own. Chestnut trees grow well in the Pacific Northwest, says Bob Rackham, horticulturist emeritus with the Oregon State University Extension Service.
The commercial chestnut crop in Oregon is still very small, and most of the highest-quality chestnuts grown here are shipped to upscale markets in California and back east.
Chestnut trees, genus Castanea, are indigenous to Europe, Asia and North America. The American chestnut, C. dentata, grew in large stands when the early settlers arrived and was greatly admired as a large and beautiful hardwood tree. Chestnut trees commonly grew to 100 feet tall with a diameter of five feet, and trees with a diameter of 10 feet were not uncommon. Growing in the open they spread into wide dense shade trees with dark green foliage.
The nuts were a staple for settlers. In the late 19th century they were harvested and shipped in great quantities to big cities in time for Thanksgiving and Christmas. Chestnut trees were common in the eastern United States, from Maine to Georgia and west to the Ohio Valley. Many species of wildlife depended on them for food, including deer, wild turkeys, bear and squirrels. The harvest from wild trees was so abundant that settlers fed them to livestock.
In forests American chestnuts took on a columnar form with few lower branches, producing straight, knot-free wood that was straight-grained and resistant to rot. It was prized both for furniture and lumber. A fast-growing hardwood, it was the dominant species in the eastern United States until the early 20th century.
But just after 1900, chestnut blight, a lethal fungus infection introduced from Asia, was discovered in New York and quickly spread among the chestnut population. By 1940, nearly all of the American chestnuts had been killed throughout the eastern United States.
The Pacific Northwest has been free of chestnut blight since the 1930s. Isolated American chestnuts brought here by early settlers are still found in various locations in western Oregon, according to Rackham. The largest chestnut tree in the country is probably one with a diameter of eight feet growing near Portland. Nevertheless, Oregon prohibits importation of chestnut trees from east of the Rocky Mountains as a safeguard.
Luckily, chestnuts have long been available from other sources. They have been cultivated in Europe and Asia for thousands of years, producing some varieties with larger nuts and greater blight resistance than the American chestnut. Some varieties of the European chestnut, C. sativa, produce nuts considered to be a delicacy in France, Spain and Italy. The Japanese chestnut, C. crenata, tends to be a smaller tree but produces large nuts at an early age. C. mollissima, the Chinese chestnut is the most blight-resistant species. Many varieties and hybrids have been developed and are available to northwest gardeners.
If you want to plant a chestnut tree in your garden, you’ll need enough space for a good-sized, fast-growing shade tree. And if you want nuts, you’ll need enough room for two trees within about 100 feet of each other. Although chestnuts have both male and female flowers on the same tree, they are not self-pollinating. Either you need to have at least two of different varieties – or you might team up with a nearby neighbor who’d also like additional shade and a fall crop of nuts.
Chestnuts need soil that drains well. They can sometimes tolerate clay soils if they’re planted on a well-drained mound or if the trees are being planted for non-irrigated timber reforestation. They’ll need to be watered in the summer until they’re established, but they’re prone to root rot in winter-soggy soils. They like slightly acid conditions, with a pH of 5.5 to 6.5.
Most varieties begin to bear by four or five years old. The nuts fall to the ground when they’re ripe, usually some time in October and over a period of a couple of weeks. Ripe chestnuts are semi-perishable and need to be picked up within a day or so of falling to prevent deterioration. They should be stored with some peat moss in cold storage to prevent too much or too little moisture and control rot.
For classic roasted chestnuts slit a cross (or at least poke a hole) in the flat end of each nut to keep it from exploding in the heat. Roast them in a shallow baking pan at 400 degrees for 15 minutes, stirring and tossing occasionally. Serve hot and peel as you eat.
Source: Bob Rackham