I had a lovely time browsing in the shop at the gorgeous RHS Wisley, and they had some nice looking garden chair cushions.
I measured the chair seat, and decided on the size I wanted (35cm square)
I had some quite sturdy fabric from Ikea hanging around at home which I cut into rectangles (twice the width of the size of the cushion I wanted to make.) I added a 2cm seam allowance all round.
I sewed it with right sides together, leaving a gap on one side to insert the filling. I clipped the corners to create neater corners when it was turned the right way out. I then also zig zagged the edges together, except on the side with the gap where I zig zagged both edges individually.
I then turned it right way out and pushed the corners out so they were square.
To create the filling I folded four layers of polyester quilt batting together and stuffed it into the cover. I slip stitched the opening closed.
To create the quilting I used contrasting embroidery thread and tied knots at regular intervals, creating a 4×4 pattern.
And here are the finished articles.