Video tutorial :

 Ch any number of sts divisible by 4 and add 5 at the end.

Foundation Row: [Puff st, ch 2, puff st] in 6th chain from hook, * skip 2 ch, [puff st, ch 2, puff st] in next ch, rep from * across to within last 2 ch, ch 1, skip next ch, 1 dc in last ch, turn.

Row 1:  Ch 4*In next ch-2 space : [Puff st, ch 2, puff st] .Rep from * to end of row. Dc in 3rd turning ch.

Rep row 1 until work measures the length you want.