Heartnut Tree Seeds (Juglans ailantifolia var. cordiformis)

The easy-open walnut. Rich flavor. Heart-shaped and remarkable.

Juglans ailantifolia var. cordiformis, the Heartnut, is a variety of the Japanese Walnut selected for its distinctive heart-shaped nuts that crack cleanly in half and release the kernel whole rather than in fragments, a characteristic that makes it the most user-friendly walnut available for fresh eating and cooking. The flavor is milder and sweeter than Black Walnut, richer than English Walnut, with a distinctive quality that regular walnut enthusiasts find genuinely different and often preferable for fresh eating. The tree grows faster than both Black Walnut and English Walnut, produces nuts earlier, and is more cold-hardy than most English Walnut varieties. The large compound leaves, up to 3 feet long, and the wide-spreading canopy create excellent shade and a bold, tropical-looking summer presence. If you are looking to buy Heartnut seeds or grow this unusual walnut from seed, this is the nut that converts people who claim not to like walnuts.

• Heart-shaped nuts that crack cleanly in half, releasing the kernel whole without the frustrating fragment problem of most walnuts
• Milder, sweeter flavor than Black Walnut with distinctive quality preferred by many for fresh eating
• More cold-hardy than most English Walnut varieties, thriving in zones 4 to 8
• Faster-growing than Black Walnut or English Walnut, reaching nut-producing size sooner
• Large compound leaves up to 3 feet long creating dramatic tropical-looking summer shade

Things you probably did not know about the Heartnut

The clean-cracking characteristic that defines the Heartnut was discovered in a Japanese orchard. The Heartnut is a selected variety of Japanese Walnut that was identified for its unusual heart-shaped nuts and the specific shell structure that allows them to crack in two perfect halves. This clean-cracking characteristic, called free-cracking in nut breeding terminology, results from a specific relationship between shell thickness, kernel shape, and the suture line between the two halves. Most walnuts shatter into fragments when cracked because the kernel fills the shell irregularly. The Heartnut's kernel shape and shell structure avoid this problem.

Japanese Walnut has the most robust root system of any temperate walnut. Juglans ailantifolia is recognized by orchardists as producing an exceptionally vigorous and deep root system that anchors the tree in challenging soils and provides superior water and nutrient uptake compared to other walnut species. This vigor is one of the reasons it is sometimes used as a rootstock for grafting other walnut varieties, similar to the way Poncirus is used as rootstock for citrus.

The nuts fall from the husks more readily than Black Walnut. Black Walnut husks can be extremely difficult to remove from the shell, requiring driving over them with a vehicle or specialized equipment to separate the fibrous green husk from the shell. Heartnut husks are thinner and release from the shell more readily, making harvest and processing significantly easier than Black Walnut and comparable to English Walnut.

The juglone produced by the roots is somewhat less allelopathic than Black Walnut. All Juglans species produce juglone from their roots, which inhibits the growth of many plants in the surrounding soil. The juglone production of Japanese Walnut and Heartnut is generally considered to be less intense than that of Black Walnut, though sensitivity among garden plants varies and some care in plant selection near any walnut species is advisable.

Growing Details

• Botanical Name: Juglans ailantifolia var. cordiformis
• Stratification: Required, 90 to 120 days cold moist stratification, recalcitrant seed, keep moist
• USDA Zones: 4 to 8
• Soil: Deep, well-drained, slightly acidic to neutral, similar to Black Walnut requirements
• Light: Full sun
• Height: 40 to 60 feet
• Spread: 40 to 60 feet
• Growth Rate: Moderate to fast, 2 to 3 feet per year

Plant it where the large compound leaves will provide bold shade and where you can harvest nuts from the ground in fall. Crack one in half when it's fresh and see why people who grow them rarely grow anything else.