FutureStarr

A What Will Grow Near a Black Walnut Tree

A What Will Grow Near a Black Walnut Tree

What Will Grow Near a Black Walnut Tree

via GIPHY

As rain falls over the black walnut tree and down through the layers of soil and rock to join the groundwater underneath, it carries bits of juglone with it into the soil. However, juglone is not very water soluble, so it tends to stay in the soil surrounding a black walnut tree, which is why there seems to be a poor growth zone that extends out from the tree itself. (The soil holds the most juglone within the black walnut tree’s canopy dripline because of the root system as well as decaying leaves and walnut shells that fall there.) A toxic chemical, juglone, diffuses from the roots into the soil, and is leached out of fallen bark, leaves, and fruit from Black Walnut trees. This chemical inhibits the growth of certain plants. (The closely related Butternut tree does the same, as well as some Hickory species.) It would be wise to not use any part of the Black Walnut tree for mulch or in compost. Also beware of leaves or nuts falling onto plants or the ground around them.

Well

via GIPHY

A chemical called Juglone occurs naturally in all parts of the members of walnut family (Juglandaceae). These trees include Butternut, English Walnut, Pecan, Shagbark Hickory, Bitternut Hickory and Black Walnut. Of these trees, it is generally only the Black Walnut which produces juglone in large enough quantities to cause problems for gardeners. Many plants are sensitive to this chemical and when grown in the vicinity of Black Walnut trees will exhibit symptoms of foliar yellowing, wilting and eventual death. The highest concentration of juglone is found in the buds, nuts, hulls and roots of the tree but can also be found in the leaves and stems. Juglone is not particularly water soluble and so does not readily move throughout the soil. The effects of juglone tend to be intensified during a drought. The area within the canopy of a Black Walnut tree is the most toxic to sensitive plants due to the high root density and the presence of decaying leaves and nut hulls. However, anywhere within the area of root growth may prove fatal to the most sensitive plants. The roots of a Black Walnut tree may spread up to one and a half times as far as the tree is tall. An established tree in your neighbor’s landscape may affect your garden as well . Decaying roots continue to release juglone, so sensitivity may continue for several years after the tree is removed.

Purdue University has informal lists of plants that tolerate juglone and those that are sensitive to it. Choose from the following list for best results in planting near black walnut trees or walnut trees grown on black walnut rootstock. Follow these guidelines for planting within the dripline of the tree and, according to the University of Wisconsin, up to 50'-80' from the trunk. Naturally you need to consider the sun and shade requirements of the plants, as well. Another source for tolerant and sensitive plants is K-State Master Gardener (Source: www.groworganic.com)

 

 

Related Articles