According to ProFlowers, a white rose signifies innocence and purity. The site states that roses symbolize hope for the future and respect and homage for a new start.
White roses were the Duke of York's heraldic sign in the 14th century. When he faced the red-rose Lancaster family in battle, the War of the Roses was begun, according to ProFlowers. Today the white rose is used in major formal settings and is a symbol of pure love. Some of the events that are more apt to show white roses include christenings, anniversaries and graduations. Some weddings also have the white rose as a central flower.