Use pansies and plant them weeks ahead of the wedding. Add the candle last minute for a great centerpiece. If the plants are growing, you just have to keep them watered to have them look great on the wedding day.
I love this for centerpieces! use a tin can base, glue on a pretty pie plate, glue in a small cake stand (or a candle holder and a tea cup saucer) and then fill in with cupcakes and flowers! beautiful centerpieces and dessert at every table!