Start by chaining in multiples of 5 plus 3.
Row 1: SC in the 2nd chain from the hook and in each stitch across.
Row 3: CH 1 and turn. SC in the first two stitches, *CH 3, skip the next three stitches, SC in the next two stitches*. Repeat to the end.
Row 3: CH 3 and turn. 5 DC into each chain 3 space all the way across. End with one DC in the last SC of the row below.
Repeat rows 2 and 3 until you reach your desired length.
Watch the step by step video to help you more: