Sterilization
According to James C. Schmidt, a horticulturist at the University of Illinois, originally putting cut flowers in a sterilized vase is important to extending the life of the flowers. Vases can be cleaned using a household dish detergent or a combination of water and bleach. Using these disinfectants ensures that there will not be any bacteria growing within the vase that could potentially cause the plant to wilt and die at a faster rate. Schmidt also claims that cutting the flowers diagonally with a sharp knife under running water ensures that they can immediately take up fresh and clean water. Re-cutting the stems periodically will ensure that there is a fresh surface from which the stems can take up water. This will allow the flowers to last even longer.
Read more about this topic: Additives For Cut Flowers