Olga,
Many years ago, when I was much younger, lol, I went to all the iris shows. I always took my bottles with the stalks in them with foam wedged between the stalk itself and the top of the bottle, and took a box and would put about six stalks in it, in the bottles. I would wad up newspapers and place between the bottles to stabilize them. It was heavy carrying them with bottles with water in them. Only put enough water in the bottle to be enough to keep the flower stalk wet, about a third of the way up the bottle. I remember being very exhausted when I got them there and all in place on the tables. I had a small car, so getting them into it without breaking the flowers was extremely difficult. I very unexpectedly won queen of show one year, it was so exciting. Good luck, whatever you use.
Dot