Long-lasting hydrangeas are the most requested blue flower. Not only do they add volume to a bouquet, but their small, clover-shaped flowers come in over 12 different varieties of blue. Their spectacular colour ranges from vast multicoloured tones of light pale baby blue and sky-blue petals all the way through to the rich, dark, almost royal indigo blue of the Mathilda. It is important to remember that hydrangeas need plenty of water and should always be placed in glass vases as they react negatively to metal containers.