Ever wondered why cut daffodils are always massed on their own, rather than mixed with other spring flowers? It is because when daffodils are cut, their stems give off a slime which dissolves in water and is poisonous to other cut flowers. If you want to mix daffodils with other blooms, you must stand the daffodils in water on their own for 24 hours, and then wash the stems. This will drain off the toxic content and you should have no further problem – unless you cut the stems again when the flowers are being arranged.
As a further precaution, you can add activated charcoal to the water in the vase. This will absorb the slime. Use 1 tablespoon of charcoal for every 2 pints of water, stirring steadily all the time as you add it.
Alternatively, you can add household bleach to the water: about three drops to each pint. This is effective as long as the daffodils are present in no more than equal proportion to the other flowers.
When there are more daffodils, you need to add more chlorine in the form of extra bleach – and this in itself can damage more sensitive plants.