What is Chinese Chestnut?

Chinese chestnut (Castanea mollissima) is a deciduous tree that produces edible nuts in September and October. This is a different species from the American chestnut that was decimated last century by a fungal canker blight that essentially eliminated it from the eastern U.S. forests. In Iowa Chinese chestnuts are grown more frequently in the southern half of the state. The first commercial plantings were planted in SE Iowa in the early 1990’s. Currently about 100,000 pounds of nuts are produced in Iowa.

At least two different Chinese chestnut trees are needed to ensure adequate pollination. Chestnut trees should be planted in soil with good drainage. Heavy clay soils should be avoided.  Spacing should be about 30 feet between trees and rows. A 30 x 30 spacing would allow for 48 trees/acre while 28 x 30 would be 51 trees/acre.  Because of the wide spacing, other crops including vegetables or small fruits could be planted between the trees for at least the first decade. Trees can start bearing the first nuts in 3-4 years.  At ten years they should be producing between 10-15 pounds of nuts per tree. Eventually after several decades the trees can reach a height of 40-60’ and a spread of 30’ and potentially produce 50 lbs. of nuts. Chinese chestnuts would not be the ideal shade tree for a play yard.  The reason being that the nuts (usually 3) are enclosed in a very spiny burr. The nuts fall to the ground when the burrs open up on the tree.  Eventually the burrs fall off and can be a bit of a nuisance.

A chestnut tree's spiny burr. Chestnuts are ready for harvest when these burrs open.
A chestnut tree's spiny burr. Chestnuts are ready for harvest when these burrs open.

There is some question on hardiness of Chinese chestnuts in Iowa. Generally they are thought to be hardy at least throughout USDA growing zone 5 (winter low temperatures of -10 to -20 F).  In 1996 some trees in SE Iowa withstood -30 F with little to no damage. In the 20 plus years since they have fared well in SE Iowa.  However, this past year brings some question into the resiliency of these trees. Many of the trees in SE Iowa leafed out late in 2019 and a few even died. This resulted in a crop of nuts that was about 20% of normal. Factors that may have attributed to this were wet to saturated soils from August 2018 through early June 2019, a sharp change from a warm October 2018 to a cold November 2018 (trees may not have hardened off), temperatures of -28 F in late January 2019 and also -10 in early March 2019.

Chestnut sizes to scale
Chestnut sizes to scale.

So the trees may not be perfect, and they do have the fore mentioned spiny burrs, but they may be well worth a try. 

Where can I get more information on Chinese chestnuts?

The Center for Agroforestry at the University of Missouri.  Has a wealth of information on chestnuts http://www.centerforagroforestry.org/pubs/chestnutpubs.php

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