I am in the process of teaching myself needle turn applique. For long thin strips, every source I have looked at uses bias tubes that are sewn using bias bars (aka celtic bars). Here is just one example of them
http://www.amazon.com/Collins-Quilte...ds=celtic+bars
Of course I have not reviewed every source there is, this is just what I have learned from about 15 different sources. The seam allowance of the sewn tube is placed on the bottom. You use the bias bars to press it in place. Remove the bias bar then use your prepared strip as stems or vines. Based on my research, most stems/long strips are not needle turned.