June 10, 2025, 10:26 am | Read time: 3 minutes
Our great-grandparents already knew that ash is a wonderful home remedy for many situations. It’s said to help a plant heal wounds as well. But is that true? myHOMEBOOK spoke with Sebastian Mühlemann from the Bauer Nursery.
Trees and shrubs occasionally need pruning, whether for rejuvenation or shaping. But what happens to the wounds left behind, which can open the door to diseases and insects? There’s a myth that tree wounds should be treated with ash. Is there any truth to it?
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Can Ash Be Used to Treat Tree Wounds After Pruning?
On the topic of whether plant wounds should be treated with ash, Sebastian Mühlemann from Bauer Nursery is skeptical: “No, it is not recommended. Wound sealants—whether tree tar, wax, ash, or other home remedies—are largely outdated in modern tree care.”
“Ash does contain potassium and other minerals, but also substances that can be harmful to plants—especially in grill or cigarette ash. This can contain heavy metals, residues from fire starters, or other toxic substances. Even pure wood ash, in my opinion, is not a suitable means to treat plant wounds,” the expert explains.
Using ash to treat tree wounds after pruning can disrupt the natural wound response. Additionally, it could even increase the plant’s risk of infection. He also emphasizes that in post-pruning care, sealing the wound is not crucial, but rather how and when you prune. The timing and technique of the cut play an important role.
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Trees do not heal like humans, as long believed, the expert explains: “They close wounds by forming new tissue around the cut area. The cambium, a thin layer of cells directly under the bark, plays a central role. This layer can form new cells—but only if the cut is made correctly. By forming new cells, the tissue is also shielded from infections. Depending on the size of the cut, this closing process can take a long time, which must be considered when pruning,” Mühlemann elaborates. Using wound protection products is mostly unnecessary and sometimes counterproductive, as they can hinder natural sealing, trap moisture, and promote fungal growth, the professional reveals.