Do you dream of a shady and luxuriant garden, perhaps with some fruit tree that offers a generous collection of autumn walnuts? You have to know that the choice of the right tree is not a trivial company. Some are resistant, productive and perfect for any garden, while others can prove to be a nightmare for the ground, if not poisonous. Let’s see together which walnut trees it is worth planting and which, on the other hand, you should avoid like the plague.
The three best walnut trees for your garden
Let’s see the most suitable specimens for cultivation.
Chinese chestnut (Castanea Mollissimo)
If you are looking for a tree that does not become too intrusive and that gives a breathtaking autumn foliage (OPS, we meant “spectacular”), Chinese chestnut is an excellent choice. It grows up to about 12 meters high and as many in width, producing shadow and, of course, delicious chestnuts. His biggest advantage? He is resistant to chestnut cancer, a disease that has practically exterminated his American counterpart. Furthermore, it is not too demanding in terms of soil: whether you have a sandy or low -ending soil of nutrients, he will adapt without batting an eyelid. But be careful where you walk: the fallen chestnuts are practically natural lego bricks.
European chestnut (Castanea Sativa)
If you have space, a lot of space, European chestnut is a real wonder. With a height that can exceed 25 meters and a thick hair, this tree can become the real protagonist of the garden. It produces tasty chestnuts and is a plant with an ancient charm. The only problem? It can be subject to chestnut cancer, then check the origin of the plants well before planting them. It grows well in slightly acidic and well drained soils, and also resists difficult conditions, even in the coastal landscapes.
Pecan walnut (Carya Illinoinensis)
Let’s face it: having a pecan walnut means always having the pretext to prepare irresistible cakes and sweets. This tree is originally from the United States and Mexico, therefore it easily adapts to various climates. But be careful: it can grow up to 40 meters high! If space is a problem, there are more compact varieties such as ‘Cape Fear’ or ‘Chickasaw’. If you want an important production of walnuts, you will have to plant at least two, as they have an alternating pollination system.
The trees in “Maybe”
The trees that we will see soon present both advantages and disadvantages, certainly worthy of careful consideration.
Aesculus Pavia (Red Hippocastan)
The first is the red horse chestnut (Aesculus Pavia), a small tree originally from large areas of the Eastern United States, known for the spectacular red-rosate blooms that earned him the nickname of “Plant Pardo”. An authentic jewel for those who want to revive their garden with lots of color, which will attract Colibrì and butterflies. It reaches a contained height, around 7-8 meters, adapting well also to reduced spaces. In addition, its fruits, although not edible for man, are highly appreciated by wildlife, aspect that makes an interesting choice for those who love to observe birds and small mammals. Another highly appreciated quality is the ability to adapt to different types of soil, regardless of the pH.
However, it has a criticality that should not be underestimated: the entire plant, from the bark to the seeds, to the leaves and stems, contains two glycosides, the exculin and the saponine escin, two highly toxic substances for man and equines. Consequently, if you play small children in your garden, inclined to explore the world bringing to the mouth everything they find, or if you have horses, the red horse chestnut certainly does not represent a prudent choice. If, on the other hand, the risk of accidental ingestion is not a problem, it recalls that the species prefers constantly humid soils and partial shadow positions to develop in a healthy and luxuriant way.
Yuglans Cinerea (American walnut)
The American walnut (Yuglans Cinerea), a member of the Juglandaceae family, is known for walnuts with a rich and pleasant flavor, loved by both man and wildlife. This tree stands out for the remarkable resistance to cold and longevity, which is around 75 years old. While belonging to the same family of the most common black walnut, it maintains more small dimensions, reaching a maximum height of about 18 meters, which makes it more manageable in a garden. In addition, in some areas of the United States, this species is considered in danger of extinction, therefore to plant a specimen can contribute to its conservation.
There are two problematic aspects to consider. The first concerns the vulnerability to the disease of the so-called butternut cancer, a fungal disease originating from the Ophiognomonia mushroom clavigignanti-juglandacearum which drastically reduced the populations of this species. The second is the presence in the roots of Yuglone, a chemical substance that inhibits the growth of many other plants in a radius of about 25 meters. Species such as azalee, rhododendrons, tomatoes and peonies are particularly sensitive to its toxicity and struggle to develop in the vicinity of an American walnut. If you decide to plant one, make sure you choose an area with wet and well -drained soil, exposed to full sun. This tree does not like competition with other plants and needs space and light to thrive.
Juglans Nigra (black walnut)
The black walnut (Yuglans Nigra) is an imposing tree, which can reach 30 meters in height and which stands out for the dark cortex, as well as for the advantage of its wood, highly appreciated in ebanisterial. The fruits, black walnuts are particularly sought after and can have an important economic value on the market.
This green giant presents a feature that makes it less suitable for some contexts: like American walnut, even black nut produces Yuglone, a substance that inhibits the growth of many plants nearby. Because of its grandeur, the area of influence of Yuglone is even wider than that of American walnut, aspect that makes coexistence difficult with many other plant species. If you want to cultivate it, it will be necessary to pay attention to the surrounding plants, choosing only varieties resistant to Yuglone.
Another critical aspect concerns water needs. To ensure abundant production of walnuts, the black walnut requires a high water supply, with about 20 liters for each fruit produced, an aspect that could represent a problem in areas subject to drought. If you choose to plant it, be sure to place it in an area well exposed to the sun, with a wet soil, well drained and rich in organic matter, preferably with a slightly acidic pH.
Trees to avoid
Let’s move on to those who have more disadvantages than benefit, in essence the least recommendable for your garden.
English walnut (Yuglans Regia)
The first on the list is the English walnut (Yuglans Regia), a species that, in addition to producing Yuglone – as already observed, toxic substance for many surrounding plants – requires more complex treatments than its American relatives, black walnut and American walnut . This variety is particularly demanding: it does not tolerate the shadow, it requires soils rich in nutrients and well drained and suffers in hot and humid environments. To prosper, it needs very specific climatic conditions, the case that make it a tree difficult to cultivate without careful maintenance.
To these already demanding requirements is added its susceptibility to numerous phytosanitary problems, including radical rot and infestations of peel flies. Another criticality concerns the plants grafted on black walnut, which can develop blackline, a pathology that causes serious nutritional deficiencies in the inner and compromising the health of the tree. While a black walnut can live over two centuries, an specimen of English walnuts suffering from Blackline could die prematurely, with a life expectancy reduced to only 15-25 years.
Walnut of luck (Cascabela Thevetia)
Do not be fooled by the appearance: the Cascabela Thevetia, also known as “walnut of luck”, hides pitfalls. Beautiful to look at, in particular yellow flowering, it is a plant that is anything but maker of luck. One of its nicknames, “yellow oleandro”, already reveals its danger: like the most famous Nerium Oleander, it is highly toxic to man.
The entire plant contains cardiac glycosides, substances that interfere with the cardiovascular system and can cause serious intoxications, even lethal. But the danger is not limited to direct contact: even the smoke produced by the combustion of the plant is toxic and may require immediate medical care. This aspect makes it particularly risky in areas subject to forest fires, where the presence could be transformed into a further health risk factor. In light of all this, cultivating the walnut of luck in one’s garden is not a wise choice at all.
Bufalo walnut (Pyrulariaria Pubera)
Those who love plants with a mysterious appearance could find intriguing buffalo walnut (Pyrulariaria Pubera), a species originally from the Appalachi region. The dark walnuts and the Gothic air resemble a sort of natural decoration, but in reality this beauty hides a malicious nature
The nuts of this tree contain a highly toxic oil that is poisonous for humans. The offending substance is the tionine of Pyrulariaria, a peptide with cytotoxic, neurotoxic and hemolytic properties, similar to the poisons of some snakes. In addition, the researchers speculate that the oil can contain the calcium oxalate, the same chemical compound that makes the Dieffenbachia apartment mortal, also known as “changes”.
Even if the peculiar aspect can fascinate, buffalo walnut is one of those species that is better to admire at a distance, without trying to cultivate it in your garden.
