Can I Use Black Walnut Leaves for Compost?

Can I Use Black Walnut Leaves for Compost?

“I have several black walnut trees in my yard. Would it be alright to use the leaves in the compost? Question from Raymond of Holt, Michigan

Answer: I would not recommend it. As you surely know, black walnut trees (Juglans nigra) excrete the toxin, juglone, which is deadly to quite a few ornamental plants. The toxin helps reduce competition, making black walnuts bad trees for small home landscapes. Who wants a deadly tree around? Still, black walnuts are beautiful and have edible nuts that feed wildlife, so they are best reserved for more wild areas or fencelines far from the home garden–unless you plant nothing but tolerant plants.

Juglone is largely excreted by the roots, but it is also found in lower quantities in the wood and leaves. The toxin can leach from leaves into compost in small quantities. That’s why you need to be careful about what you plant near a walnut tree and where you put walnut leaves, which are best taken to the woods, fenceline, or bagged for disposal.

Because you have a black walnut tree, it would be prudent to get to know plants that are resistant and sensitive to these trees. Please click here for a great list provided by the Morton Arboretum, a world-class tree resource.

Symptoms of Black Walnut Toxic Syndrome

Keep in mind that there is no cure once sensitive plants have been significantly impacted by juglone. Exposure signs include yellowing, wilt, stunted growth, and finally death. It may take plants months to die after exposure.

Happy gardening,

Jessie Keith

Black Gold Horticulturist


Are Sunflower Leaves and Petals Toxic?

“Are the petals and leaves of garden sunflower blooms toxic to eat?” Question from Caroline from Evansville, Indiana

Answer: Stick to the seeds when it comes to eating sunflowers. The flowers and leaf and stem hairs contain a mixed bag of chemicals called sesquiterpene lactones that commonly cause bad reactions in humans–both on the skin or if ingested. In fact, they commonly cause dermal allergies, so it’s smart to use gloves when cutting stems for arrangements.

These chemicals can also poison cattle. According to the Canadian Poisonous Plants Information System, cattle poisoned by sunflowers show the following symptoms: “circulatory failure, swaying of hind quarters, excitation, and collapse 1-3 h after ingestion. Postmortem findings include lung edema, small hemorrhages and congestion of intestinal blood vessels, and dark- colored blood (Cooper and Johnson 1984).” YUCK!!!

Fully matured sunflower seeds do not contain these bad chemicals, but immature seeds can, so be sure seed heads are fully mature and dry before harvesting any sunflower seeds for eating.