Why does Round 2 use chain 1 between stitches?

The chain gives the petals room to flare. It keeps the double crochet stitches from bunching tight.

Can I skip the Sepals round?

You can, but the chain-7 loops hold the Flower Base in place. Without them, the petals have nowhere to attach.

Count twelve double crochet stitches around the magic circle. If the count is off, the later rounds will not lie flat.

Worked in yellow yarn.

Magic Circle and First Stitches

Round 1Create a magic circle and chain 2; crochet 12 double crochet stitches into the magic circle; pull tight and slip stitch into the first stitch to close the round; chain 2 to start the next round. (12)

Increasing Stitches

Round 2In each stitch, crochet 2 double crochet stitches; after every two double crochet stitches in the same stitch, chain 1; repeat this (2 dc, ch 1) in all 12 stitches; slip stitch to close the round and chain 2.

Pattern Repetition (Cluster A)

Round 3Crochet 1 double crochet in the first stitch; crochet 2 double crochet stitches in the second stitch; chain 1 — this is Cluster A; repeat Cluster A around (1 dc, 2 dc, ch 1) for a total of 12 clusters; slip stitch and chain 2 to end round. (12 clusters)(12)

Pattern Repetition (Three-Stitch Cluster)

Round 4Treat every three stitches as one cluster; in the first and second stitch, crochet 1 double crochet each; in the third stitch, crochet 2 double crochet stitches and chain 1; repeat this 12 times; slip stitch to finish the round. (12 clusters)(12)

Round 5: Increasing Size

Round 5Crochet single crochet stitches around; in the last stitch of each cluster, crochet 2 double crochet stitches and chain 1; repeat for all 12 clusters. (12 clusters)(12)

Worked in green yarn, attached to the Base.

Round 1Attach green yarn with a slip knot; crochet 2 single crochet stitches into any stitch; chain 7; skip next 2 stitches, crochet 1 single crochet in the third stitch; repeat chain 7, skip 2, and 1 single crochet until end of round; slip stitch into the first single crochet to close the round.

Worked in green yarn, using the chain-7 loops from the Sepals round.

Cluster A forms the 5-treble petal base; Cluster B forms the space between flowers.

Round 1In the first chain loop, crochet 1 single crochet, chain 3, crochet 1 treble crochet and chain 1, repeat (1 tr, ch 1) until there are 5 treble crochets, after the last treble, chain 3, crochet 1 double crochet to complete Cluster A; in the next chain loop, crochet 1 single crochet, chain 7, slip stitch into the fourth stitch from the hook, chain 3, crochet 1 single crochet into the same loop to complete Cluster B; alternate Cluster A and Cluster B around the circle.

Worked in yellow yarn.

Crochet one flower for each Cluster A made in the Flower Base round.

Popcorn Stitch (6 times per flower)

Round 1Pull yarn through and chain 3; in the first space, yarn over and pull up a loop 4 times (leave incomplete); yarn over, pull through all loops, chain 1 to secure; repeat for all six spaces in the flower base; slip stitch into the third chain of the starting chain 3; chain 3. (6 popcorn stitches)

Petal Formation

Round 2In next stitch, crochet 1 double crochet; chain 3, crochet 1 single crochet into the space between stitches; in the same stitch, crochet another double crochet; chain 3, crochet 1 double crochet into the space; in the next popcorn stitch, crochet 1 double crochet; chain 3, double crochet into the space, and again into the popcorn stitch; chain 3, crochet 1 single crochet into the space; repeat for all 6 popcorn stitches; slip stitch into the first stitch to finish the flower.

Base, Rounds 1 through 5 about 30 minutes, because five rounds build the shaping fast.
Sepals, Flower Base, and Flower Petals about 20 minutes, because the chain loops take patience.

cotton, worsted weight The coaster holds its shape better and resists heat longer.
acrylic, DK weight The coaster turns softer and slightly smaller; a smaller hook helps.