Rice is thrown at weddings as it is considered to be a seed symbolic of life and prosperity. It was traditionally thought that throwing rice would help increase the fertility of the married couple to ensure that they had children.
Many venues do not allow rice to be thrown at a wedding because it becomes slippery when it is wet and may cause accidents. Popular alternatives include flower petals, leaves or even sunflower seeds. Wedding guests in France throw wheat and people in Italy throw candy to symbolize sweetness between a wedding couple. Some couples prefer that guests do not throw anything that will make a mess outside and ask that guests blow bubbles at them instead.