How do you preserve fresh-picked flowers for at least 3 days?

I'm going to sell flowers Mums and Roses. But from what I notice, roses wilt very fast. Is there any way I could maintain their fresh look?

How do you preserve fresh-picked flowers for at least 3 days?
A few drops of bleach in the water to hinder bacteria, plus sugar. There is also a cut flower preservative you can buy to put in the water (ask at a flower shop). Additionally you have to keep roses COLD.
Reply:Put some coffee grinds in the water or sugar. when putting the flowers in a vase or bucket.