it's easier (I think) to add to each block seperately than a lon strip to a whole row. cut you strip the width you want (I usually go for 2-1/2", gives 2" finished) by the length of one side of your block. sew it on, press and measure the bottom of the block plus the added strip, that's the length for that piece. the blocks on the outside perimeter will of course have more than 2 strips