If they are still attached to the roses, you could probably store them in the crisper/vegetable drawer of your refrigerator.

Wendy, I used dried rose petals for a basket the flower girl was carrying (and was going to toss) in a wedding I did last week and I just kept them in a brown paper bag and tossed them once a day to be sure they were all dry. I usually dry rose petals on a suspended screen for good air circulation.

For fresh I would make sure to toss or fluff them once or twice a day so they don't start to mold or mildew - I have never tried to keep rose petals fresh before - please let us know how that works out.

Linda