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Questions and Answers: 2022

Question: Hello! I have a question about planting a kalmia angustifolia near a large established juniper bush. I note that these …

• Question

  Hello! I have a question about planting a kalmia angustifolia near a large established juniper bush. I note that these plants are allelopathic to conifers. I was going to plant it a few feet away, but I won't if it will impede the juniper lifecycle or cause it harm. Would a kalmia angustifolia harm a juniper bush and if so, how? Are the allelopathic chemicals distributed by the root system? Is there guidance for a safe distance to plant it away from the juniper?

  Answer

  Dear NPTrust, good morning. There are many allelopathic plants, some of which are well known (e.g., black walnut). It is important to realize that allelopathic plants do not harm all plants (i.e., there are species that can grow in close vicinity and do just fine where others will not be able to). So, it depends on the species involved. I do not know about the interactions between American-laurel and juniper (the ones you asked about). I'm guessing that if you plant them far enough apart (a few meters) you wouldn't have any major issues. Best wishes.