Answer #1: Aspirin, we have all heard this tip and when I have tried it I have had some success. Other ideas that I have come across are;
1. putting the flowers in a fridge for a few hours before arranging them.
2. Cutting a little piece off the bottom of each stem every few days.
3. Add a little Lemon Juice to the water.
4. Grow your own, they are always fresher.
Patti Moran Dublin-- Comment
Answer #2: When you get home with you bouquet trin down the ends with a super sharp blade and use warm, not hot water. The plant food that florists sell or supply are usually good an prevent the water going bad. -- A Marcusson Comment