1. Add 1 or 2 drops of bleach per gallon of water. Plants die more quickly because their stems are exposed to bacteria.
2. Cut stems at an angle because it creates more surface area for the stem to absorb water. Do not cut them straight across.
3. Spray flowers with hydration and protection spray, which can be found at any floral supply store. Below is a photo of the type that I use. This can be used for live plants or cut flowers.