Floral preservative
Mary used for floral preservative lemon-lime soda and some bleach.
She mixed one part lemon-lime soda (regular, not diet) to three parts water, along with 1/2 teaspoon of bleach.
The citric acid in the soda help the water travels up the stems to the flowers more rapidly, while providing food in the form of sugar.
The bleach helps fight the growth of bacteria, allowing the flowers to stay hydrated and fresh.
You can use some commercial floral preservative.