When she came to pick it up, she loved it so much that she gave me three MORE blankets to do!
Create a foundation row through the blanket. I did (sc, ch1) all the way around. You can add more chains depending on how close you want your blanket stitches to be. sl st with first ch.
Ch 1 and sc in same st. 1sc in next 2 sts, *ch 3, sk 2, 1 sc in next 5 sts, repeat from * around. sl st with first sc. Ending this row can be difficult because you never really know how many stitches you made around the entire blanket. What I found to be effective is, once you get to the last 15 or so stitches, see how close you are to making the join perfectly even (that is, having the pattern of 5sc, sk 2, finish off evenly), and if you need to make some adjustments, the best one I found is to do 4sc instead of 5sc for as many of those 5sc groups it takes to work out evenly.
ch 1 and sc in same st. *7 dc in ch3-space, sk 2 sc, 1sc in next st (this should be the middle of the 5sc), repeat from * around. Fasten off. If you had to make some 4sc instead of 5sc groups, just alternate placing the 1sc in the 2nd and 3rd sc of the 5sc group. It should look fine!