You may have heard that to keep flowers fresh you should keep them refrigerated. Do NOT put your bouquet in the fridge.
A refrigerator is the opposite of the commercial floral cooler, pulling moisture out instead of creating a humid environment. Make sure that the stems of the bouquet are in plenty of water and keep it in your coolest room.
Ask that your florist spray the flower crown with a protective flower spray such as "Crowning Glory".
Have something that the flower crown can sit on...around a vase, an upside down bowl, etc, so it is elevated and doesn't get flattened. Since there are no exposed stems, this can go in the front of the fridge. The back can be too cold and freeze/ruin the flowers.