Smash or pierce the stems, or use blunt scissors, as this destroys the water vessels and inhibits water uptake, and causes bacteria to multiple more quickly and over a larger area. It also causes the flower undue stress which shortens its life.
Mix daffodils and narcissi with other flowers. They emit latex from their stems when cut, which is known as `daffodil slime', and shortens the life of other flowers. Keep daffodils alone in vases, or use the special bulb cut flower food which makes them safe to mix with other flowers. You can place the daffodils in a bucket of water for at least 12 hours on their own and then arrange them with other flowers, making sure you do not cut the stem again.
Put flowers near ripening fruit – it releases tiny amounts of ethylene gas which prematurely ages flowers. Dying flowers do the same so always remove them from the vase.
Place flowers in a draught which chills the flowers, or in bright sunlight which encourages bacteria to breed. Keep them away from over-warm central heating.
Put copper coins, aspirin, lemonade, or bleach in the water. They're popular tricks but they don't work, and they can't feed your flowers adequately. Homemade formulas are messy, time-consuming and do more harm than good. Follow the care and conditioning tips for best results.