Herb: Black Walnut

Latin name: Juglans nigra

Family: Juglandaceae (Walnut Family)

Medicinal use of Black Walnut:

The bark and leaves are alterative, anodyne, astringent, blood tonic, detergent, emetic, laxative, pectoral and vermifuge. Especially useful in the treatment of skin diseases, black walnut is of the highest value in curing scrofulous diseases, herpes, eczema etc. An infusion of the bark is used to treat diarrhoea and also to stop the production of milk, though a strong infusion can be emetic. The bark is chewed to allay the pain of toothache and it is also used as a poultice to reduce the pain of headaches. The juice from the fruit husk is applied externally as a treatment for ringworm. The husk is chewed in the treatment of colic and applied as a poultice to inflammations. The burnt kernels, taken in red wine, are said to prevent falling hair, making it fair. Green husks are supposed to ease the pain of toothache. A tea made from the leaves is astringent. An infusion has been used to lower high blood pressure. It can be used as a cleansing wash. The pulverized leaves have been rubbed on the affected parts of the body to destroy ringworm. The oil from the ripe seeds has been used externally in the treatment of gangrene, leprosy, and wounds. The sap has been used to treat inflammations.

Description of the plant:


30 m
(98 feet)

May to


Habitat of the herb:

Rich fertile woods and hillsides in deep well-drained soils.

Edible parts of Black Walnut:

Seed - raw or cooked. A sweet, rich distinctive delicious flavour it makes an excellent dessert nut and is also widely used in confections, cakes etc. The kernel is hard to extract and the oil it contains quickly turns rancid. The unripe fruits can be pickled. The seed is borne in solitary fruits or in pairs and is 3 - 4cm in diameter. The nuts can leave a permanent stain on clothing. An edible oil is obtained from the seed. A sweet taste but it tends to go rancid quickly. Used as a seasoning in bread, squash and other foods. The tree yields a sweet sap that can be drunk or concentrated into syrup or sugar. It is tapped in spring.

Other uses of the herb:

A brown dye is obtained from the nuts, husks and bark. It does not require a mordant. The husks can be dried for later use. A brown dye is obtained from the leaves and stems. It does not require a mordant. The dye turns black if it is prepared in an iron pot. The leaves can be dried for later use. The husks are rich in tannin. The green fruit husks can be boiled to provide a yellow dye. The husks can be made into a high quality coal (does the report mean charcoal?) and is then used as a filter. It was used in gas masks. The woody shells on the fruits have been used to make jewellery. Insects are said to avoid the walnut tree, hence it is often used as a poor man's insect repellent. When rubbed on faces, walnut leaves are said to repel flies. The leaves repel fleas and have been used as a strewing herb. They are also used as an insecticide against bed bugs. The ground up husks are also insecticidal. The leaves produce substances that depress the growth of other plants. These substances are washed onto the ground by rain and inhibit the growth of plants beneath the tree. The roots also produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.). An alternative ingredient of "QR" herbal compost activator. This is a dried and powdered mixture of several herbs that can be added to a compost heap in order to speed up bacterial activity and thus shorten the time needed to make the compost. Wood - very ornamental, heavy, hard, strong, close-grained, very durable. Easily worked, it glues well, does not warp, shrink or swell much and takes a good polish. It weighs 38lb per cubic foot. A very valuable timber tree and possibly the most sought after wood in N. America, it is used in cabinet making, the interior finishes of houses, furniture, airplanes, ship building, veneer etc.

Propagation of Black Walnut:

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. The seed can also be stored in cool moist conditions (such s the salad compartment of a fridge) over the winter and sown in early spring but it may then require a period of cold stratification before it will germinate.

Cultivation of the herb:

Rich fertile woods and hillsides in deep well-drained soils.

Known hazards of Juglans nigra:

The plant has occasionally been known to cause contact dermatitis in humans.

Plant information taken from the Plants For A Future.