Black Walnut Tree Guide

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Black Walnut Trees Care Guide

Although black walnuts prefer a sunny spot, they are drought intolerant. This makes it essential that they receive plenty of water, especially when they are young.

It's also worth knowing that the roots contain a substance known as juglone. This is a toxic compound that can be deadly to nearby plants, so it's wise to look for plants that tolerate juglone.

Black walnuts thrive in USDA hardiness zones 5a through 9a. This means that they need about 25 inches of rain as well as 140 days without frost each year. Moist, fertile soil that drains well is best, and black walnuts prefer soil that is loam, silt loam or sandy loam.

A north or east facing site is best when planting a black walnut tree. Avoid bottomland or valleys that offer minimal airflow, as this may lead to damage during frosts. Water young trees once a week through the spring and summer. More mature trees only need water once every two or three weeks.

Black walnut trees may be fertilized once per year in the early spring. A 15-15-15 fertilizer frequently is recommended, but black walnut trees are most frequently in need of nitrogen, so a fertilizer that emphasizes this nutrient may be a good alternative.

Design Ideas

Black walnut trees have a lovely, spreading canopy that offers a great deal of shade. They also have an extensive root system and a very deep tap root that helps mature trees to maintain hydration during long summer months.

Keep in mind that black walnut tree roots produce juglone, so choose companion plants with care. Options include forsythia, barberry, Daphne, Rose of Sharon and the snowball hydrangea.

Also check out this blackwalnut tree guide on USDA