I go to a wharehouse sale every year. I have 13 balls of Gina I'm a bit short to make a sweater with snow flakes. I'm wondering if I can make it an inch short then block it to stretch it. The yarn it 97% wool, 3% nylon

i'm afraid the nylon content might bring the yarn back to where it should be....

what i would suggest, if you have already started knitting it, place the stitches on a holder or piece of yarn and try washing and blocking and see what happens. if you have not started yet, do a gauge swatch and attempt the blocking. that is probably the only way to know for sure.

I'm going to knit it an in shorter, if I need to I'll pick up and knit an inch in white at the bottom.