Techniques used in this stitch (British term / American term):

Chain stitch – ch

Slip stitch – sl.st

Double crochet / Single crochet – dc / sc

Treble / Double crochet – tr/dc

Stitch - st

Round 1: Make 5ch and work in last ch * 1tr/dc, 1ch, rep from * 10 more times, sl.st in 3rd ch, sl.st in space of 4ch.

Round 2: Make * 5ch, 1dc/sc in next space of 1ch; rep from *10 more times, 2ch, 1tr/dc in 1st ch.

Round 3: Work 5ch, 1tr/dc in space of 2ch and tr/dc below, * 1ch, make 1tr/dc + 2ch + 1tr/dc in space of 5ch; rep form * 10 more times, 1ch, sl/st in 3rd ch.

Round 4: Make 3ch, 3tr/dc in space of 5ch, 1dc/sc in space of 1ch. Then work 7ch, insert hook around 3ch of 1st round (see pictures) and work 1dc/sc.

Make 2ch, turn and work into space of 7ch: 2dc/sc, 10tr/dc. Then work 4tr/dc in space of 2ch of 3rd round.

Repeat last step: *1dc/sc in space of 1ch, 7ch, 1dc/sc around next tr/dc of 1st round, 2ch, turn, work 2dc/sc + 10tr/dc into space of 7ch, 4tr/dc in space of 2ch; rep from * 9 more times.

Work 1dc/sc in space of 1ch, 7ch, 1dc/sc around next tr/dc of 1st round, 2ch, turn, work 2dc/sc + 10tr/dc into space of 7ch, sl.st in 3rd ch.

Round 5: Work 1ch, *insert hook through 2tr/dc of 1st petal (see picture) and work 1dc/sc, 5ch; rep from * 11 more times over each of the next petal. Then work 5ch, sl.st in ch.

Round 6: 1ch, work 7dc/sc in each of the next space of 5ch, sl.st in ch.

Round 7: 8ch, skip 7st, *1dc/sc in next, 7ch, skip 6st; rep from* 9 more times, 1dc/sc in next st, 7ch, sl/st in 1st ch.

Round 8: 9ch, *1dc/sc in dc/sc below, 8ch; rep from * 10 more times, sl.st in ch.

Round 9: 10ch, *1dc/sc in dc/sc below, 9ch; rep from * 10 more times, sl.st in ch.

Round 10: Make 4ch, * work 4tr/dc + 3ch + 4tr/dc in next dc/sc below, 1ch, 8tr/dc in next dc/sc, 1ch; rep from* 4 ore times, 4tr/dc + 3ch + 4tr/dc in next dc/sc below, 1ch, 7tr/dc in 1st ch of round below, sl.st in 3rd ch.

Joining

Join motifs in last round. For shells with 3ch between work next steps: 4tr/dc in dc/sc below, 1ch, 1dc/sc in space of 3ch of the opposite motif, 1ch, 4tr/dc in thr same dc/sc below.

For 8tr/dc shells work next: 3tr/dc in the same dc/sc, drop the loop from your hook, insert your hook through 2 loops of the corresponding stitch on the opposite motif, grab the dropped loop with your hook and pull it through the stitch. Work 1tr/dc the same dc/sc and repeat preceding step. Finish the shell working 4tr/dc.

To make petals in two or more colors, change the yarn each time after you make dc/sc in space of 1ch.