Flowering shrubs add wonderful color, and sometimes fragrance, to the garden when they burst into bloom. These bushes can also provide structure, shade and privacy in the garden. Many can be planted in a row to create a formal hedgerow or massed as an informal hedge. Some favorite flowering shrubs include lilacs, spirea, tree peonies, butterfly bushes, rose of Sharon shrubs, hydrangeas, azaleas and honeysuckle. When buying flowering bushes and shrubs for sale online, make sure the variety will grow in your hardiness zone. Other factors to consider include the shrub's mature height and spread, light requirements (full sun, partial shade or full shade), bloom time and flower color.