In pattern stitch, four 3-dc groups and 9 rows = 4"/10cm.
Gauge is not critical for this project.
Chain (ch), double crochet (dc), single crochet (sc), slip stitch (sl st)
rev sc (reverse single crochet) Work single crochet in opposite direction by inserting hook in next stitch (to the right if right-handed, and to the left if left-handed), yarn over and draw up a loop, yarn over and draw through both loops on hook.
The color is changed every 2 rows. To change color, work last stitch of old color to last yarn over. Yarn over with new color and draw through all loops on hook to complete stitch. Fasten off old color. Proceed with new color.
With B, ch 183 loosely.
Row 1: 3 dc in 8th ch from hook (beginning ch counts as ch 3 of foundation ch, dc, ch 1), *ch 1, sk next 3 ch, 3 dc in next ch; repeat from * across to last 3 ch, ch 1, sk next 2 ch, dc in last ch, turn—Forty-five 3-dc groups, 45 ch-1 sps, and 1 dc at each end.
Row 2: Ch 3 (counts as first dc here and throughout), 2 dc in first ch-1 sp, *ch 1, 3 dc in next ch-1 sp; repeat from * across to turning ch-sp, ch 1, 3 dc in turning ch-sp; change to C, turn—Forty-six 3-dc groups, and 45 ch-1 sps.
Row 3: Ch 4 (counts as dc, ch 1), *3 dc in next ch-1 sp, ch 1; repeat from * across to last 3-dc group, dc in top of turning ch, turn.
Row 4: Ch 3, 2 dc in first ch-1 sp, *ch 1, 3 dc in next ch-sp; repeat from * across to turning ch-sp, ch 1, 3 dc in turning ch-sp; change to next color in sequence (see below), turn.
Repeat last 2 rows until piece measures approximately 56"/142cm from beginning and changing color every other row in following color sequence: D, E, F, G, *A, B, C, D, E, F, G; repeat from * as needed and end with a G row. Fasten off.
Round 1 (RS): With RS facing, join A with sc anywhere in edge of afghan, sc evenly spaced all the way around, working 3 sc in each corner; join with sl st in first sc, DO NOT TURN.
Round 2 (RS): Ch 1, rev sc in each sc around; join with sl st in first sc.
Fasten off. Using yarn needle, weave in all ends..