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heartnut

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.

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