Heartnut
(Juglans ailantifolia var. cordiformis)

The heartnut is a native of Japan that is well suited to the Great Lakes fruit growing regions (zone 6), a region similar to its native regions in Japan. The nut is named after the shape of the nut, as the illustration shows. It is considered a seed sport of the Japanese walnut and not a different species. The Japanese walnut is an oval nut, unlike the heart shaped form of the heartnut. The Japanese walnut usually cracks out very poorly, making it unsuitable for commercial production. There are no selected common Japanese walnuts in propagation. They tend to be hardier than the heartnut form of the nut and so efforts should be made to find improved cracking Japanese walnut selections for colder regions. When heartnut seeds are planted, a wide variety of nut shapes and sizes can be produced by the offspring, from good and poor cracking types to oval, very poor cracking, typical Japanese nuts. For this reason, commercial orchards are not advised to plant seedling heartnut trees, but should plant only grafted trees.

Though the heartnut tree will grow in colder regions than zone 6, it can be affected by late frosts. Since the tree is terminal bearing, the nut flowers are housed in the tip buds of the trees. These buds are the first to open in the spring and are sensitive to cold spells in April and May. Frost injured flowers will abort and so reduce the crop. We only recommend commercial orchards for zone 6. Graft survival is also best in zone 6 to 7.

11-year-old heartnut

The heartnut tree is best suited to well drained fertile sand and clay loam soils with a pH of 6 to 7. They are suited to soils where black walnut and butternut grow wild. They are vigorous trees, growing 50 to 100 cm or more in a year reaching a height of 15 m and a spread of 20 to 30 m. The large lush compound leaves are largely unaffected by most insect pests. Grafted trees will begin to bear in 1-3 years, with commercial production expected in 6-8 years. The trees are long lived with annual production estimated at 1-3 tons per acre.

Heartnut trees are selected for several important characteristics.
These include:

  1. Cracking Quality The nut must crack reliably on the suture (the seam that holds the shell together) and release the kernel (nut meat) in one or two pieces. The kernel should fall out easily with no pieces bound in the shell. Normal shaking and dropping should allow the kernel to fall free as would occur in a cracking machine. This cracking characteristic must be consistent from year to year.
  2. Production The tree must be hardy enough to produce full crops in the region where they will be grown. Nut set should be high with a low number of aborts during the growing season. The crop weight after harvest will be the final consideration. Consistency of cropping from year to year is also important.
  3. Kernel Quality The kernel should be plump and pale yellow in colour. Uniform pale grey and beige tones are also acceptable. Variable tones and shrivel are undesirable. The flavor should be mildly walnut in character with no bitterness.

Heartnut Cultivars

A number of selections have been made that meet the above criteria and others are being tested and evaluated on an ongoing basis.

Imshu - This selection was made by John Gordon. It is a seedling of Schubert. It has rated highly for hardiness, cracking quality and other nut qualities. It often drops out whole kernels. It is a good producer of large nuts. It is early season ripening, about September 30 in the Niagara Region.

Campbell CW 1 - Doug Campbell planted Etter seedlings (from the Etter grove in Pennsylvania). It is rated high for hardiness, cracking quality, production and nut quality. Kernels are a light golden colour and drop out in halves reliably. Nuts are a medium size and ripen about September 30.

Campbell CW 3 - Doug Campbell planted this Etter seedling. It is very similar to Campbell CW 1 in nut and tree qualities. Nuts are slightly larger than CW 1 and ripens the end of the first week of October. Nuts drop out in halves.

Campbell CWW - Doug Campbell planted this Etter seedling. It also is similar to CW 1 in nut size, production and nut quality. It ripens about the same time as CW 3. Nuts drop out in halves.

Fodermaier - This is an older heartnut selection from Dover Plains NY. It is rated high for cracking quality and production. It produces a large nut of with good quality. Nuts drop out in halves. It ripens mid October and being a later nut, it is recommended for long frost free season areas like the Niagara area.

Heartnut trees are only partially self pollinating. This means that two or more seedlings or different grafted selections should be planted. For commercial plantings a planting plan like the one shown below will help growers to establish trees with permanent pollinators in place. It is advisable to consider field drainage tiles between the rows and irrigation for prolonged dry spells of 6 weeks or more during the growing season.

Click here to view the Heartnut planting plan

 
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