How can I lengthen an existing curtain?
+2
Suggested Project Book
You could sew a ruffle across the bottom if you like that look. If not, you can get a coordinating fabric and sew a straight band across the bottom.
Sew it on, stitch witchery, or Aleene's fabric glue will also work.
Add a contrasting border of fabric on the bottom, I would make it at least 6" to look purposeful.... https://www.google.com/search?hs=V4M&q=curtain+with+a+large+border+on+bottom&tbm=isch&source=univ&client=opera&sa=X&ved=2ahUKEwjm07n7gcfjAhXHj1QKHWwmA6AQsAR6BAgJEAE&biw=1473&bih=692
You could sew a coordinating panel onto the bottom.
You could use ring clips to help give it some extra length or you could add extra fabric to the top or bottom in a coordinating color/pattern