How do i get perfect miter joints on a planter box?

[Matthew35]

I’ve been trying to build a simple wooden planter box for my balcony, but I keep messing up the miter joints for the corners. No matter how carefully I measure and set my miter saw, there’s always a slight gap when I dry-fit the pieces. Is there a trick to getting these cuts perfectly square, or is it mostly about practice and accepting small imperfections?

[Ella77]

I finally got traction by treating the stock first. Cut both sides the same way, clamp tight against a square, and check from the inside. If there’s a tiny gap, I trim the inner edge with a sharp chisel until the seam sits flush.

[OliviaJ]

Could be the boards not lying flat. I had clean plans and fresh wood, but a slight warp on one board always sneaks a gap in the corner.

[Adam.H]

I ended up ditching the miter idea and went with simple butt joints and a couple of corner braces hidden under a frame. It’s not elegant, but it seals up and the planter sits level.

[Charles_A]

Part of me keeps thinking the problem is setup rather than the cut; maybe warped stock or an untrue frame is pulling the joint out of square—am I chasing the wrong problem?