Are your flowers in a place that is exposed to the sun? We have tried ice cubes when it was in the mid 90's at our stand. I think it helped. What helps more is to take them home and refrigerate them for a while, rotating stock and bring them back when the sun goes off the stand or the day cools some. Another way I have tried is to set the cups of flowers in a plastic box half full of water with ice floating in it. That seems to work pretty well too. Freeze ice in some plastic cups or jugs and set them in so that it doesn;' melt too fast like ice cubes do.

Anita,
I've wondered the same thing. When I brought roses to the Farmers Market they opened so quickly in the heat that the next week I tried bringing only buds showing color. The buds pretty well opened up, too. It was hard to sell fully open roses although they were very beautiful. I'm sure they would not last very long once they were taken home. Haven't tried using ice in the water since they are between blooming cycles, but I will and will let you know.
Glenn

I appreciate the replies. I think the only way to find out is to experiment!

I'm not a seller. I'm taking flowers from my garden to a week-long conference. I provide the arrangement for the main conference room. The flowers have to survive a 3 1/2 hour drive, and last all week. We do have airconditioned rooms, which helps the flowers last. I change the arrangement daily. Last year, by the end of the week, I was mostly using wildflowers I found in a meadow. I was thinking of putting ice in the water for the drive. Also, I am learning to cut the flowers a bit earlier in their bloom--when they are just opening.

i also put ice in my cut flower water on a day in the 90's at the market and i am sure it helped. a few flowers drooped, but not even close to the normal numbers. the problem was that i didn't have enough ice - it was melting too quickly. the water didn't stay near as cold as i would have liked it to. i was playing around with the idea of drilling vases/larg-ish holes in a piece of styrofoam and putting water, ice and cuts directly in the holes. i would think the ice would melt more slowly. i'll give info if/when i get to it....