The types of joint used in almost every mass produced planter is the common butt joint that is held together by nails or staples. While the butt joint does have its applications, it is just about the weakest kind of joint you can use in wood working.
We use rabbet joints or lock miter
joints at the corners and we use tongue and groove joints between the
boards that make up a panel. Other joints used in our construction are
dados, mortise and tenon, lap joints and finger joints. Increasingly, we
are using Miller Dowels where appropriate.