The first rule of thumb with flowers is WATER WATER and more WATER. It’s the lifeblood of those beauties. Flowers soak up warm water faster so make sure the water is at least room temperature and preferably a bit warmer. The only flowers that like cool water are the cool temperature flowers such as daffodils and tulips. And although they like warm water, never put your cut flowers in direct sunlight or near a heat source such as a fireplace or heating vent.
Always cut the bottom of each stem at an angle to help soak up more water. If you do this every day when you change the water the flowers should last several days longer. If the flower has a woody stem such as lilacs, make a slice up from the bottom of the stem, The cut should be a few inches long to help them soak up the water in the vase.
Those little packs of perservative that you get from the florist really do work. But what if you’ve cut your own flowers or you’ve run out of the magical little dust? The Brooklyn Botanical Garden has come up with a homemade mixture that works as well as the commercial preservatives from the florist .In a quart of warm water, mix 1 teaspoon sugar, 1 teaspoon bleach, and 2 tablespoons lemon or lime juice. This works well in cutting down the bacteria and will give your flowers several extra days in the vase. I find that this also works will with my Christmas tree. I can put it up the weekend after Thanksgiving and have it last until well after January 1st.