The black walnut tree is a highly prized species, not only because it provides edible nuts, but because the wood itself is extremely strong and beautiful. If planted in favorable conditions, black walnut trees can live for more than 200 years. Keep in mind that the tree will not bear nuts until it is at least 10 years old, and the best crops come out of trees that are over 30 years old.
Where to Plant Black Walnut
The first thing a black walnut tree needs is deep, rich clay loam soil, preferably with a pH of 7.0. The tree will not thrive in rocky, sandy or gravelly soil. The loam should go down at least two feet before hitting bedrock or harder-packed soil. The deep soil is necessary for the taproots to spread. As the black walnut grows, the taproots spread out rapidly, but the tree itself doesn't grow quickly.
Black walnut trees require a lot of moisture; they prefer a minimum of 25 inches of rain per year. They are most happy with at least 35 inches of rain a year.
While the trees prefer a large amount of moisture, they do not like to be in standing water. Plant them in well-drained soil and be sure they aren't in an area that gets more then a few days of standing water a year.
Take care to select a planting location far from gardens and other plantings, as black walnut roots give off a chemical that can stunt the growth of nearby plants.
Black walnut trees will not grow on steep slopes that face south or west, as they are too hot and dry. They will grow well on river terraces and hilly north- or east-facing terrain. To minimize a black walnut's exposure to wind, you can interplant the trees with another species. Be careful that the other species will not shade the black walnut; they do not like to be shaded. When you buy a black walnut tree, ask the nursery about companion trees you can plant.
Diseases and Pests
Black walnut trees are susceptible to several types of blight. Bacterial Blight causes black spots on leaves, along with holes and blotches on the nuts. Occasionally, the blight causes new shoots to die back.
Walnut Blight affects younger trees. It does the most damage if it happens during cool and wet periods, around flowering time. For both blights, the only treatment is to cut out the damaged parts. Both blights can be prevented by planting in soil with a pH above 6.0, keeping the nitrogen level low and by not over-watering.
Black walnut trees are also susceptible to Leaf Blotch and Walnut Leaf Gall Mite. Leaf Blotch is a fungus that not causes brown blotches on the leaves and fruit. It can also make the nuts turn black and fall off or cause the tree to drop leaves. This disease spreads well in wet weather. The only treatment is to burn fallen leaves to prevent the spread of the fungus.
Walnut Leaf Gall Mites raise bumps on the leaves that resemble caterpillars. The mites are extremely tiny. They nest in the buds and destroy them before they can turn into leaves. This pest is hard to climinate, but the damage it causes is not life-threatening to the tree.
Sometimes gardeners plant things knowing that there will not be instant gratification but a big payoff in the future. So it is with planting pecans and hickories. You may have to wait, but both pecans and hickories produce delicious nuts that have many proven health benefits.
It's easy to learn how to grow a beech tree that will reward you for years to come with its lovely foliage.