When I made my little quilt ‘Blue Birds’ last month, I decided to add a mitred border on it.
Here’s how I went about it- I’m sure there are lots of different ways to do it and this is probably a mix of all of them! First, cut four strips the width of the required border plus 1/2″ for seam allowances, and in the length of each side plus at least 4″. So if the quilt is 10″ wide and 14″ long, I would cut two lengths 14″ long and two lengths at 18″long.
Sew each length to each side and top and bottom, stopping the stitching 1/4″ from the end each time. Mark the stopping point with a pencil before you stitch- it needs to be accurate. There will be about 2″ of the strip hanging off each end. Press it open.
With the top facing up, arrange it so one strip is laying straight with its end extending out to the side, and then fold the other strip so that it makes a 45* angle. I used a pin in the corner to just keep it still on my padded surface while folding it. side
Use a ruler with a 45*angle marked on it to line it up with the folded corner and make sure you have the fold exact. Press.
Put a piece of tape over the fold- this is to keep it in place while you turn the quilt over.
When it’s turned over to the other side and the two strips are lined up parallel together, you will easily see the crease that was pressed into it.
Sew from the corner point (where the previous lines of stitching ended) straight out along that crease to the edge. Lining up the two strips like this also means that there will be a tiny gap along the crease in the tape on the other side, so when sewing along this diagonal line your needle won’t sew through the tape. If it does, you can easily remove it.
Turn the quilt over and press again- voila! a perfectly-sewn mitred corner! You can then trim the seam.