Should You Grow a Black Walnut Tree in Your Home?

Trees are highly beneficial for homeowners. These great plants can add value to a residential property, spruce up your landscape and provide much-needed shade.

Not every tree, however, is beneficial to property owners. Some, unfortunately, have a dark side. One such tree variety is the black walnut tree.

Black Walnut Tree History

The black walnut tree, also known as Juglans nigra, is a tree that naturally grows in North America and sheds its leaves annually. This deciduous tree has been valued since the early days of European settlement due to its hardwood and edible nuts. Introduced in 1629, the black walnuts were among the first North American species of trees to be brought to Europe.

Throughout history, the black walnut tree has been used for various purposes. Its hardwood is prized for its strength and durability, making it an ideal choice for furniture and cabinetry. The nuts can be used for multiple culinary applications, from baking to roasting. They are also a valuable source of nutrition, containing essential fatty acids, fiber, and protein.

The black walnut tree is an important economic species, with the nuts fetching high prices due to their flavor. The delicate and sweet nutmeat is highly sought for gourmet cooking and baking. As a result, the trees are harvested from forests and planted on farms to meet the market’s demand. Like other edible plants, such as the rainbow corn plant, the black walnut tree is an important economic species that can immensely benefit local communities.

In addition, black walnut timber is highly valued for its strength and durability. The rot-resistant wood makes it an excellent choice for outdoor furniture and other applications. Its dark color and striking grain pattern make it an attractive option for fine furniture and cabinetry. High-class joinery, flooring, doors, and paneling are all produced from the sapwood of this species.

The value of the black walnut tree isn’t limited to its edible nuts and high-quality wood. Every part of the tree has medicinal properties that can be used for various purposes, such as repelling mosquitoes, aiding dermatological conditions, treating diarrhea, and acting as a laxative. It can also be used as a treatment for parasitic worms. So many countries’ economies heavily depend on the black walnut tree due to its multiple uses.

What is a Black Walnut Tree?

Photo by David Burns via Flickr Creative Commons

Black walnut trees are native to the eastern and central United States. These plants can live up to 200 years and are one of the six walnut tree species found in the country.

A black walnut tree provides a lovely canopy to property owners, stretching up to 100 feet in height. What’s more, this plant can branch to 50 inches in diameter.

The flowers of a black walnut tree appear in late spring. Since this tree is monoecious, it will have both female and male flowers and self-pollinate. Female florets will form in small groups on a small spike and will have three to six florets. On the other hand, male florets will hang down cylindrically from the stems.

Apart from providing shade and growing flowers, the black walnut tree produces fruit, which the plant drops in late summer through October. The fruit is heavy and has the size of a baseball.

If you are willing to crack the tough outer shell, you’ll find that the “meat” inside the fruit is edible. Take note that the earthy and sweet nutmeat is well worth the effort. You can eat the nuts found in black walnut trees in their raw form. You also have the option to use these nuts for other purposes.

These include:

  • Adding the nuts into the baking (bars and cookies)
  • Grinding them to produce a unique flour
  • Using them as a topping on cakes and ice cream
  • Cooking them as a sweetened candy nut

Growing a Black Walnut Tree

You can plant this type if you reside in USDA hardiness zones 5a through 9a with at least 140 frost-free days and a minimum of 25 inches of precipitation per year. Black walnut trees flourish in moist, fertile, deep yet well-drained soil with a texture ranging from sandy loam to silty clay loam.

If you want to grow a black walnut tree, you could either obtain a seedling from a local gardener, try to germinate your own by planting nuts or buying a tree. Note that this tree will attract squirrels, so pre-emptive caring for this plant is in order.

Use a cloth to cover the planting area. Then, lay a layer of mulch (leaves or straw) over that cloth to stop repeated freezing and thawing. Make sure that you mark the planting site. If you are ready to grow your black walnut tree, there are a few steps you need to take. Here are some cool gardening tips to get you started:

Soil Requirements

The black walnut tree prefers well-drained, loamy soils with a pH range between 6.0 and 6.5. It is important to remember that this species will not tolerate wet or waterlogged soils. This is because the roots of this tree are sensitive to too much moisture and can be easily damaged by flooding or over-irrigation.

Temperature and Watering 

The black walnut tree requires full and direct sunlight, so it does not do well in the shade. It needs about 35 inches of annual precipitation, an average temperature of 55 degrees Fahrenheit, and at least 170 growing days to thrive.

When watering the black walnut tree, it is crucial to ensure it reaches its root system. This can be done by hand or with a drip irrigation system. It is advisable to water the tree deeply but infrequently; once every two weeks is usually sufficient.

Fertilizing and Pruning

Fertilizing is an essential step for ensuring the health and growth of a black walnut tree. It should be done in early spring, using a balanced fertilizer. It is important to follow the instructions on the package carefully, as too much fertilizer can damage the tree’s root system.

Pruning is also vital for the health of the tree. Pruning should be done in early spring or late winter before growth begins. This will promote healthy and vigorous growth and reduce the risk of disease and pests. The tree should be lightly pruned when nuts form to shape and encourage fruiting.

Flowering, Pollination, and Fruiting Stage

The black walnut tree blooms from May through June, with the male flowers being yellow-green catkins that droop from the tree and the female flowers in spikes. While trees are capable of self-fertilization, they are primarily wind-pollinated.

After fertilization, the female flowers develop into walnuts, ready for harvesting in late August or September. The tree will begin producing nuts approximately ten years after it has been planted. The most optimal nut production typically occurs when the tree reaches 30.

Black Walnut Tree Companion Plants

Companion planting is an integral part of successful gardening. While the juglone secretion from black walnut trees can be toxic to some plants, a few plants, primarily trees, can tolerate the presence of a black walnut tree. These include quince, nectarine, peach, cherry, persimmon, and plum. Additionally, you can choose oaks or hickories if you want taller trees. You may also consider planting hackberry, poplar tree, black locust, catalpa, Eastern redbud, Canadian hemlock, most maples, red cedar, and pagoda dogwood near the black walnut tree.

Black Walnut Tree Varieties and Types

Walnuts come in many varieties, some suitable for growing at home. The most common type of black walnut is the English walnut (J. regia), native to Europe, the Middle East, and North Africa. In addition, several other native and hybrid varieties can be grown in the home garden, including Thomas black walnut (J. nigra ‘Thomas’), Shagbark hickory (Carya ovata), and Chinquapin (Castanopsis).

Propagating Black Walnut Tree

Seed Propagation

The black walnut tree can be propagated using seeds. The best time to collect walnuts for propagation is in September and October. Due to the thick husk, removing them immediately and rinse with water is important. The nuts should then be placed in a pail of water, and the ones that float should be discarded. The remaining nuts can then be stratified and planted in the spring, with the area protected from animal pests.

Grafting and Budding

Grafting and budding are other techniques used to propagate black walnut trees. The best time for grafting is in early spring when the sap starts to flow. The most common method is whip grafting, which can be done with various tools. Budding requires a unique tool called a budding knife and is done in the summer months when the bark slips.

Effective Black Walnut Tree Plant Care Tips

Site Selection

When selecting a site for your black walnut tree, it is essential to consider exposure to sunlight and protection from strong winds. The tree should be planted in a sunny spot with plenty of space to spread its branches. Surrounding plants should be chosen carefully, as the juglone secretion can be toxic to some species.

Soil Preparation

Before planting the tree, it is crucial to prepare the soil. It should be loosened and amended with organic matter such as compost or manure. Additionally, a layer of mulch should be applied to conserve moisture and keep weeds at bay. The pH levels should be tested and amended according to need.


When the tree is established, it should be mulched annually with a thick layer of organic matter. The mulch should not be too deep to avoid smothering the tree. But it should be thick enough to prevent weeds from growing and conserve moisture.

Pruning and Pest/Disease Control

The black walnut tree should be pruned regularly to promote healthy growth and reduce the risk of pests and diseases. Common issues include the grey squirrel and walnut-leaf blotch. Fungicides and insecticides should also be used to treat any infestations or diseases.

Winter Care

This hardy tree can cold winters and will benefit from a layer of protective mulch. But regular watering is important to ensure the tree remains healthy in winter. In addition, keep an eye out for late frosts and protect your seedlings by temporarily bringing them indoors.

Are Black Walnut Trees Bad for Gardens?

A black walnut tree produces a toxic chemical that can kill garden plants like cucumbers. Photo by Kelly Neil on Unsplash

If you’ve decided to plant a black walnut tree in your home garden, you’ll want to stick with that plant. This tree produces a compound called Juglone. This chemical can kill a variety of plants, including the following:

  • Asparagus
  • Cucumber
  • Potato
  • Thyme
  • Buttercup
  • Lily of the Valley
  • Petunia
  • Grape
  • Cypress
  • Eastern White Pine
  • Silver Maple
  • Russian Olive

Juglone, even in low doses, can be toxic. Simply removing the offending black walnut tree from a potential garden area will not immediately solve the problem. Plants susceptible to black walnut toxicity can still die from the decomposing roots of a walnut.

If you don’t want to stick to planting a single tree, stay away from black walnuts and opt for other alternatives, such as poplar or persimmon trees. If you insist on having a garden next to the black walnut tree, make sure that you choose plants that are impervious or tolerant to Juglone.

These include:

  • Carrot
  • Onion
  • Squash
  • Bellflower
  • Dandelion
  • The Glory of the Snow
  • Hawthorne
  • Hibiscus
  • Witch Hazel

Are Black Walnut Trees Profitable?

Although black walnut trees produce a chemical that’s unfortunately toxic to other plants, they can help you make more money.

Black walnut logs fetch premium prices (they have since the 1700s). A single tree can bring you up to a whopping $20,000.

So why are black walnut trees highly valued? The answer is in the wood. Furniture- and cabinetmakers love working with the tree’s close-grained wood because of its exceptional durability and attractive color. The logs are so valuable that “walnut rustlers” remove the trees in the dead of night and even use helicopters in their operations.

However, note that the black walnut tree is not a fast-growing plant. The tree takes a decade before it can even produce nuts. If you have the patience and the time, you could plant this tree as a legacy and a priceless gift for your grandkids and children.

A black walnut tree is a great plant that produces shade and tasty nuts. If you’re going to plant this tree, consider the toxic compound it produces and refrain from planting vegetables and flowers that will die from the chemical.

Frequently Asked Questions

1) How tall do black walnut trees grow?

A black walnut tree can reach up to 40 meters (130 feet) with a trunk diameter of 1.2 meters (4 feet).

2) How long does a black walnut tree take to produce nuts?

A black walnut tree will begin producing nuts approximately ten years after it has been planted. The most optimal nut production typically occurs when the tree reaches 30.

3) Are black walnut trees poisonous?

The black walnut tree secretes juglone, a toxic compound to some other plants. Therefore, it’s important to be careful when selecting companion plants for your black walnut tree.

4) What are the benefits of black walnut trees?

Black walnut trees offer many benefits, including providing hardwood for furniture and cabinetry, edible nuts, medicinal properties, and attractive grain patterns. It is also an important economic species due to its multiple uses.

5) How do you identify a black walnut tree?

Black walnut trees can be identified by their leaves, which are alternate and pinnately compound with 11-23 leaflets. The bark is dark gray-black, and the fruits are round, with a thick green husk that splits open when ripe.

6) Can you grow a black walnut tree from a nut?

It is possible to grow a black walnut tree from a nut. The nuts should be collected in September and October and stratified for several months before planting in the spring. This will ensure successful germination.


The black walnut tree is an important economic species, with its highly valued hardwood and edible nuts. Growing a black walnut tree at home requires careful consideration of soil conditions, temperature and watering requirements, and companion planting. The tree can be propagated by seed, grafting, or budding, requiring regular pruning and pest/disease control.

Due to their multiple uses, black walnut trees will continue to be a valuable resource. If you are thinking about growing one in your home, these tips should help you get started. You can enjoy this species’ benefits for years with proper care and maintenance.

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