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.

Pollination:

Heartnut trees are only partially self pollinating. This means that two or more seedlings or different grafted selections should be planted.

Seed Sowing:

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame. You need to protect it from mice, birds, squirrels etc. The seed usually germinates in late winter or the spring. Plant out the seedlings into their permanent positions in early summer and give some protection from the cold for their first winter or two.

Cultivation details:

The heartnut tree is best suited to well drained fertile sand and clay loam soils with a pH of 6 to 7. Plants produce a deep taproot and they are intolerant of root disturbance 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.

Harvesting:

Heartnuts are harvested when they fall from the tree. The thin hull on the nut always remains attached at harvest, but falls off after drying. Dry nuts for several weeks in a cool, dry place. Crack a few nuts every couple of days to check their dryness before storing. Heartnuts store well and have a long storage life.

Heartnuts may be eaten raw, but develop their best flavour when used in candy, baked goods or toasted in a frying pan with a little butter and salt until they darken. They have a milder flavour than black walnuts.

Except for Chinese chestnuts, all nuts discussed in this publication are high in oil. They store best if nut meats are extracted, placed in an air-tight container and frozen, because oils turn rancid more rapidly at higher temperatures. Frozen nuts may be kept for several years or longer without loss of quality. The next best way to store nuts is to shell them and keep them in air-tight containers in the refrigerator.

Unshelled nuts should be placed in a cool, dry, well-ventilated location such as a garage, shed or cool root cellar. Put them in mesh bags to promote good air circulation. Properly cured nuts may keep a year or longer in a cool place.

Walnut and Hickory nut kernels are easier to remove if they are soaked in water for 1 to 2 hours, drained and then held in a closed container such as a covered bowl or jar for 10 hours.

Cultivars:

Bates - A medium-size nut, the kernel percentage and flavour are very good. Matures early. A vigorous, hardy tree, it bears well.

Brock - A large nut, the shell is perfect, kernel percentage and flavour are very good. A moderately hardy, heavy bearing tree.

Campbell

Calander - A medium-size nut, the kernel averages 31% of the nut, it cracks out well, has a very rich flavour and matures early. A hardy, heavy-bearing tree, the flowers are protandrous.

Caloka - A small to medium-size nut, averaging 170 to the kilo. The kernel averages 36% of the nut.

Canoka - A large nut, averaging 110 - 170 to a kilo. The tree bears heavy crops annually, though it requires a relatively long growing season to fully ripen the nuts. The tree comes into growth 1 - 2 weeks later than most other cultivars and so often escapes damage from late frosts.

Char - First year introduction produces a very large nut. Selected in Korea and imported, it has been grown here for several years. Tree is a very vigorous grower and precocious with thin shell and high ratio of kernel to shell crack out. Trees have an upright growth habit that is desired for planting in a yard setting. Nut is heart-shaped and fills well.

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.

Etter - The large nut cracks out easily, the kernel percentage and flavour are very good. An exceptionally hardy, productive tree, it produces high quality seedlings for breeding and selection.

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 averaging 120 to the kilo. 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.

Frank - The medium size nut cracks well. The tree comes into growth 1 - 2 weeks later than most other cultivars (though not as late as 'Canoka') and so often escapes damage from late frosts.

Gellatly - This variety has a large-sized nut. Shell smooth, light brown in color, and of medium thickness; cracks easily, and the large light-colored kernel is of the highest quality. Bears early and abundantly, the nuts hanging in long bunches of from eight to twenty-two; and tree has distinct flower and bud characteristics. Not self-fertile, consequently pollenizers have to be planted with this valuable variety. Over eighty per cent of the seedlings from this tree have produced heartnuts. Heartnut also referred to as J. cordiformis.

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.

Jewel Box Heartnut- This cultivar of Heartnut was developed in Kentucky. It has a very large nut, and is a good producer; steady cropping every year that late frost isn’t a problem.

Locket -

Marvel  - The medium to large nut cracks well and is of good quality. A vigorous, hardy, productive tree, it has withstood temperatures down to -30°c or lower. It is a good pollinator for the cultivar 'Wright' and is itself pollinated by that cultivar.

Mitchell Hybrid - A butternut X heartnut hybrid that is very productive had has heartnut shaped nuts. Vegetates early.

Rival - A medium-size nut, it cracks well when dried and has a good quality and flavour. A hardy, productive tree, it has withstood temperatures down to -30°c or lower. It is a good pollinator for the cultivar 'Wright' and is itself pollinated by that cultivar.

Rhodes  - A medium to large nut with a thin shell, it cracks easily and has a very good kernel percentage. The flavour and quality are excellent. A moderately hardy tree, it flowers late and bears heavily. It is probably self-fertile.

Rosefield - Large, dark brown nut with wide kernel cavity, making it very easy to remove the meat whole or in halves. Flavour quite mild and delicate. Self-fertile, making it a good companion for most heartnuts.

Schubert - A relatively large nut, it cracks out well and has an excellent flavour. A heavy bearing tree.

Simcoe 8-2 -

Stealth -

Wright - A medium to large nut, it is very free cracking and has a pleasant flavour that resembles the butternut (J. cinerea). A heavy bearing, very hardy tree, it is not resistant to broom disease. A good pollinator for the cultivars 'Fodermaier', 'Marvel' and 'Rival'.