Black Walnut
- Zone 3
Characteristics of the tree
The black walnut (Juglans nigra) is a fast-growing walnut tree, whose nut is prized for its distinctive flavour and medicinal properties. It is also our most precious North American hardwood; many people plant it as an investment.
The black walnut is well-known for its delicious and distinctively-flavoured nuts. The smooth and round walnut shell is highly perfumed. The flesh of the walnut is sweet, spicy and aromatic, and many will tell you that they make the best pies.
It is also prized for its nutritional value and medicinal properties: it is high in essential minerals and fatty acids, and the hulls have been also shown to have antibacterial properties.
The black walnut is a fast-growing tree that can reach 30 metres high and a 10-metre branch spread. This walnut tree needs a sunny spot and well drained, rich soil. Well-drained clay is its favourite place to be. The tree will survive being drowned in water for two weeks in spring, but no more than that.
The black walnuts that we propagate will grow in temperatures as low as those experienced in zone 3, but needs to be in zone 4 or warmer to produce nuts. It’s important to note, however, that our statement about hardiness does not necessarily apply to all black walnuts, as the source of the seed will determine how cold hardy the tree will be. Many black walnuts are not hardy to zone 3, but our seedlings originate from parent trees that have shown superior cold-resistance.
The black walnut is a member of the Juglans family. It is infamous for producing juglones, said to be allelopathic to various plants inclusive of apple trees, tomato, potato, cabbage, eggplant, blueberry, azalea, rhododendron, lilac, red pine and the like. For a more complete list of plants intolerant to juglone click here.
However, evidence on the precise effect of juglones on plants is mixed, with some studies even suggesting that it may be the density of the roots, rather than any particular substance, that prevents plants from growing well beside them. See this article for more details.
There seems a good amount of general evidence to suggest that other plants have difficulty competing with black walnuts, so this should be considered when choosing where to plant them.
The black walnut (Juglans nigra) timber is rare in the face of continually rising demand, and prized for its use in furnishings. It is therefore very valuable. Planting a stand of black walnuts can constitute a genuine long-term investment.
If you are planning to harvest black walnuts for their monetary value, we suggest planting them at half of the recommended distance, (planting them closer together will also encourage them to grow straight and help to increase the value of their timber) and harvesting every second tree when they are large enough, leaving the remainder to increase in size. The remaining trees will meanwhile benefit you with a walnut harvest each year.
Black walnut can grow to impressive heights, reaching 30 metres or 100 feet at maturity, with a spread of 10 metres! However, although it is a relatively fast-growing tree, it will still take it quite a lot of time to reach its maximum height! In 20 years, as shown in this illustration, you can expect it to reach approximately 8 metres in height.
You should note that this illustration is meant only to give a general indication of what you can expect, and the growth of your tree might look somewhat different. The development of a tree depends on the soil type, irrigation, fertilisation and climatic conditions. What we show here is based on our observation of the growth of black walnut in zone 4, in rather poor soil. In zone 3, growth will probably be slower, while in a rich soil it could be faster.
As walnut shell is very hard, you will need a more solid tool than the common nut cracker to get the nut out of the shell. Aside from a specialised nut-cracker, the best tools we have found for accomplishing this task efficiently and easily are (in order of preference):
- An arbor press
- A bench press
- A hammer, having wrapped the nuts in a towel (this is more messy and harder to control than the previous two, but also works in the absence of another method.)
Once cracked, a metal toothpick or a knife with a narrow blade are helpful tools for extracting the flesh. We can promise you that it is well worth the effort! The nuts can be stored in a cool, dry place (in their shells, but with the husk removed) for about two years. It is important to store them in the shells, as without the shells they will turn rancid much more quickly.
All our walnut trees are sold bare-root, without pots. They have been cultivated directly in our soil. Bare-root trees must be taken out of the ground and shipped during their period of dormancy, which is why we only ship trees in the spring. A big advantage with these kinds of trees is that they take up very little space, and can therefore be easily shipped by mail all over Canada!
This photograph shows a 2-3-foot walnut tree, just like one that you might receive. Depending on the height you choose at the time of purchase, the tree might be somewhat taller (3-5 feet); or it could be smaller (1-2 feet).
