Hi, in construction cedar is used as a rot resistant material that can be placed on direct ground contact and not rot which might suggest there is some chemical in the
wood that does not allow it to break down (unlike other softer woods) with soil contact. In the house, cedar has traditionally been used as a natural pesticide (eg cedar lined closets, cedar moth balls). Underneath live cedar
trees it is difficult to get anything to grow and is known to emit an allelopathic toxin or a 'natural herbicide' that prohibits growth of other plants. Having said this some people think using cedar in raised beds will stunt the growth of plants that are placed inside them for the reasons previously mentioned. However, does cedar continue releasing allelopaths long after the wood has been cut down and dried in a kiln? And if it does, is it
enough to stunt or kill the little growies in your raised bed? I have no idea but for your sake I hope it works fine. I just don't like raised beds for various other reasons , personal preferences that's all.
Good question.