{"id":2786,"date":"2019-08-02T00:05:14","date_gmt":"2019-08-02T07:05:14","guid":{"rendered":"https:\/\/depts.washington.edu\/hortlib\/pal\/pal-question-576\/"},"modified":"2023-08-08T12:51:52","modified_gmt":"2023-08-08T19:51:52","slug":"lilac-and-elm-wood-and-allelopathy","status":"publish","type":"pal","link":"https:\/\/depts.washington.edu\/hortlib\/pal\/lilac-and-elm-wood-and-allelopathy\/","title":{"rendered":"lilac and elm wood and allelopathy"},"content":{"rendered":"

I have a huge planter to fill but don’t want to buy that much soil so I want to partially fill it with wood. I’m going to plant herbs in it but I wanted to know if the wood I have would make eating the herbs inadvisable. I have roots and branches from a snake bark elm and some large pieces of lilac. None of the wood is treated but I know some wood is poisonous and wasn’t sure about these two.<\/strong><\/p>\n

 <\/p>\n

Before you go ahead with using wood to fill in the planter, another trick
\nyou might try is to put an upended smaller pot inside the large pot, if
\nthe planter is too deep. What you are looking for is a potting medium
\nwith good drainage.<\/p>\n

I am not familiar with snakebark elm (there is a snakebark maple, and a
\nlacebark elm–might it be one of these?) so I can’t give a conclusive
\nanswer about its wood or roots. The phenomenon of plants which are toxic
\nto other plants is called allelopathy. The most famously allelopathic
\ntree is the black walnut. Apparently, lilac wood (Syringa vulgaris) has
\nthe ability to raise the phenolics content in the soil, according to a
\n2004 scientific article<\/a> (now archived) I found, from the 2nd European Allelopathy Symposium.<\/p>\n

To be on the safe side, I would avoid using the lilac and elm wood as
\nfiller in your planter, since there are better options.<\/p>\n

You may find the information below useful:<\/p>\n

Local gardener Mary Preus’s book, The Northwest Herb Lover’s Handbook<\/em>
\n(Sasquatch Books, 2000) offers a recipe for potting soil for herbs grown in containers:<\/p>\n