I don't know that I would use tulle unless this quilt is a wall hanging that will no put it at risk. Another thing I recently discovered at a workshop I attended using tulle on a quilt (wall hanging) was using black tulle somehow worked better for quilting as the object was not washed out for lack of color or tone.
I would use a White on White for the jar and be sure that the stems were appliqued outside the jar with the ring of the jar over the stems. You may want to get a be of dimension by adding a bit of gray to make the bottom of the jar. You may have a bit of hand embroidery stitching to provide for the rest of the bottom, to make the circular aspect as well as the upper ring. Of course these are my thoughts and it is always up to the quilter. I can wait to see what you are doing!