Question
Will untreated cedar boxes affect plant growth? If yes, treat with what?  If not, sweet!  35*15*12 size  Want to grow as organic as possible, even water leakage issues, sealant.  Want good tomatoes, not cedar or sealanted!!!  Hope you understand my quest?

Answer
Cedar is perfect for raised beds or growing boxes.  I use untreated cedar in my yard.  The construction has lasted nearly 10 years now with no degradation.  Cedar will not adversely affect the growth of the plants.  It is durable, sturdy, and will not leak.  

Good luck with your project, and have a nice week.

Regards,

Mike