Hand tied bridal bouquets are very favored by today's bride. Florists such a myself like bouquet holders, since having fresh flowers requires a constant water source. You can have both by creating a "mock hand tie". You'll have the look and feel of a hand tied . . . yet your flowers will last so much longer being nourished by fresh flower throughout your special day.
Although my personal preference is usually a SuperWet, the Belle holders shown below are a great product. Just be sure an replenish the water as the flowers draw up the moisture very quickly.
First step is to "float soak" - meaning you allow the foam to soak up water gradually instead of forcing it underwater. It becomes saturated very quickly, and won't have the danger of dry pockets of foam that may happen if you force the foam below the water line.
Always use water treated with a professional flower food such as Crystal Clear. This cheap little products goes a long way towards keeping your flowers alive longer!
Secure your soaked bouquet holder in some type of weighted container. A narrow necked vase weighted down with marbles or rock works well. Just remember wet foam and flowers can become heavy and topple forward when you are least expecting it if you don't have it firmly secured.