Is there a way to stretch a knitted piece of material, like a bag strap or scarf so that it is longer, WITHOUT actually adding more rows? Say I’ve finished my scarf or whatever, but it’s not long enough. I’ve been wetting the piece and then stretching it between two posts and letting it dry. Are there any other ways?
I don’t really mind if the piece gets skinnier. It’s cheap, cheap yarn, so I don’t really have to worry about wasting $1000 on my yarn. 
If it was wool, it would stretch and stay that way. For acrylics, I’d say the wet and stretch method will work until you wet it again.
Ingrid, you are a wealth of knowledge, thanks so much ;)!!!
So, Red Heart Super Saver yarn would be, I’m assuming, wool?
I’m really clueless about yarn types and things, so I really appreciate all of you peoples’ help!!
No, Red Heart Super Saver is 100% Acrylic. It probably won’t hold the stretch for too terribly long, unfortunately.