Sewing the curve
For a pieced block, sew one background to the petal first: match the center notches, pin the petal tip into each corner, and sew with the background on top. Add the second background the same way and press toward the backgrounds. For appliqué, turn the allowance under on the dashed line, folding the points first, then stitch the petal corner to corner on its background square. To make circles, turn every other block a quarter turn so the petal tips meet four together at every other corner; set them all the same way for diagonal chains.
How the template is drawn
The petal is where two quarter circles meet: each side is a circle the size of the block, centered on one of the block's other corners. So the petal runs corner to corner, its points are right angles, and petals in neighboring blocks meet at the corners. Each pieced background is a drunkard's path background whose curve reaches the corners.
Example: an 8 in pieced block with 1/4 in seams. The petal's sides are 8 1/4 in arcs on an 8 1/2 in square, and each background is an 8 1/2 in square with a 7 3/4 in quarter circle cut away.
Questions
Should I piece or appliqué an orange peel?
Piecing gives crisp curves and points at the corners but takes careful pinning. Appliqué is easier to line up: turn the edges under, or use fusible web and cut on the line with no allowance.
What size background square do I cut for appliqué?
The finished block plus two seam allowances: 8 1/2 in for an 8 in block with 1/4 in seams.
Why is this petal longer than some free templates?
It runs the full diagonal of the block, so petals meet at the corners as in a pieced block. Sew Can She's appliqué petal for an 8 in block is about 10 in long with blunt ends, against 11 5/16 in from corner to corner here.
How do I know the printout is the right size?
Measure the square at the top right of each page: it must be exactly 1 in (or 25 mm). If not, print again at 100% or Actual size, not Fit to page. From a phone, save a PDF and print that at 100%.
Sources: Sew Can She, Orange Peel Quilt Block tutorial; Missouri Star Quilt Co., The Orange Peel Quilt tutorial (Jenny Doan).