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 flattened 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 6-8. Wind machines as used in the wine industry can eliminate most damaging spring frosts and allow the heartnut to be grown in colder climates including zone 5b.
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. More information is available on growing heartnuts in the SONG handbook called Nut Tree Ontario, A Practical Guide free to new members of EC&SONG that take out a new 3 year membership.

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 gold 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.

Attention Growers!
We are always interested in new selections that offer the above characteristics. We are especially interested in additional qualities as follows. If you have a seedling heartnut tree that meets these qualities contact a member of SONG or the Grimo Nut Nursery at www.grimonut.com

  1. A narrow suture that allows for a larger internal cavity.
  2. A thinner shell with a well-sealed suture that cracks easily with a hand cracker.
  3. A hardier heartnut tree for zone 5 with acceptable nut characteristics.
  4. A later leafing improved selection that avoids late spring frosts.

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.

Protandrous cultivars release pollen before their female bloom is receptive. Protogynous cultivars are the opposite. Even though heartnut trees are partially self-pollinizing, by matching a protandrous cultivar with a protogynous one, complete pollinization is assured.

'Imshu' - This selection was made by John Gordon. It is a seedling of Schubert. It has rated highly for hardiness. It has exceptional cracking quality, yielding a high percentage of whole kernels. It has a light kernel colour and a fine mild flavour. It is a good producer of medium size nuts. It is early season ripening, about September 30 in the Niagara Region. It is a protogynous cultivar, so it is a suitable pollinizer for all of our protandrous cultivars and vice versa.

'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 medium size and ripen about September 30. It is a protogynous cultivar like 'Imshu'.

'Campbell CW 3' - Doug Campbell planted this Etter seedling. It has been reported as one of the hardiest selections. It is very similar to Campbell CW1 in nut qualities. Nuts ripen a week to ten days later than Imshu. Though it is a smaller more compact tree than other heartnut cultivars, it is a heavy producer with large nut clusters and so is usually more productive than trees its own age. Nuts drop out in halves. It is a protandrous cultivar.

'Simcoe' - (formerly 'Simcoe 8-2') was selected from a seedling planting at the Simcoe Station Experimental Farm. The tree was a guard tree for a heartnut experimental grove, and was provided by Doug Campbell. It is a slightly larger Valentine heart shaped nut that freely drops out a mixture of whole and half nutmeats. It bears on a two to three year cycle producing heavy and lighter crops. It is protandrous cultivar. Nuts ripen 2 weeks after Imshu.

'Stealth' - John Gordon introduced this selection from his 50 acres of experimental seedling plantings in Amherst, NY. It is an elongated nut, a bit larger than Imshu with a thick husk. It is a moderate producer. The nut meat drops freely out of the shell whole. It is a protandrous cultivar. Nuts ripen 2 weeks after Imshu.

'Adelphia' - was introduced by Dr. Thomas Molnar of Rutgers University. The nut is slightly larger than Simcoe with a perfect Valentine heart shaped shell. It is a good producer. The nut meat drops freely out of the shell whole most of the time with careful cracking. It is protandrous cultivar and so is best matched with one of our two late pollinizers. Nuts ripen 2 weeks after Imshu.

'Locket' - introduced by John Gordon has a nut that is a bit larger than Imshu. It is productive but not quite as good cracking out. The nut meat drops freely out of the shell in a mixture of whole and half meats most years. It is a protandrous cultivar and so is best matched with either Imshu or Campbell CW1. Nuts ripen 1 week after Imshu.

Heartnut trees are only partially self-pollinizing. 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 pollinizers 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.

For marginal heartnut growing areas of zones 5b-6, wind machines like the ones used in the commercial wine regions of the Niagara area, would help prevent bud killing spring frost conditions.

Heartnuts benefit from the tree shelters in the nursery. The trees like the shelter and grow better in them. Without the shelter, the lush leaves would bend the tree down. A 3 foot shelter would help newly planted 1-3 foot heartnut trees in the orchard too.

Click here to view the Heartnut planting plan

 
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