The Northern California walnut tree has a single trunk, and the tree.

Jun 06, Leaves of walnut trees contain a chemical that is toxic to some plants. The chemical is juglone. Juglone is most concentrated in black walnut trees, but other walnut tree varieties also have the juglone toxin in the leaves, etc.

Leaves from walnut trees should be composted for at least one year before using on plants. Walnut leaves can be composted because the juglone toxin breaks down when exposed to air, water and bacteria. The toxic effect can be degraded in two to four weeks. In the soil, breakdown may take up to two months after the living walnut tree has been removed.

Mulch or woodchips from black walnut are not recommended for plants sensitive to juglone. Black walnut leaves may be composted separately, and the finished compost tested for toxicity by planting tomato seedlings in it. Sawdust mulch, fresh sawdust or chips from street tree prunings from black walnut are not suggested for plants sensitive to juglone, such as blueberry or other plants that are sensitive to juglone.

May 25, Laidback Gardener Tip of the Day Yes, You Can Compost Black Walnut Leaves Black walnut (Juglans nigra) and, to a lesser extent, other walnuts (Juglans spp.), as well as their close relatives, the Continue Reading.

Aug 06, It isn’t advised to use walnut leaves as mulch right where you plant, but we’ve had no problems using a small amount on paths. Use them to cover the ground where you don’t want plants to grow. When in doubt, go for the hot composting method. Jun 26, Juglone (the chemical exuded by Walnut trees) is at its least concentration in the wood, but it's still there and still harmful. Considering how expensive Walnut is, how it's processed, and how well-known it's killing properties are; idk if you'll see it in a mulch.

Epsom salt is always a good addition, most soil is lacking Mg. Feb 11, How about using black walnut nut hulls as mulch? Black walnut trees have large concentrations of juglone and hydrojuglone (converted to juglone by some plants), which is toxic to many plants.

Juglone concentrations are highest in walnut buds, nut hulls and roots but are also found in lesser quantity in leaves and stems.