It is always annoying when you have one (single) flower and all your vases are with wide necks. I have a solution! For single-flower-vase you will need a balloon, scissors and a glass (or a vase, or even a plastic bottle). Cut a balloon as I showed at video and stretch it on your glass (vase, bottle...). Fill glass with water and insert your flower into a hole (balloon's "x-neck"). You can use any balloon of any colour. Good luck!