Conditioning cut flowers before displaying them in a vase extends their lives as long as possible. Most cut flowers' lives are shortened by their stems' inability to absorb water effectively after they are cut. When the stems are exposed to the air after they are cut, air bubbles form at the base of the stems and prevents water from reaching the flower petals. Conditioning the flowers helps to prevent these air bubbles from developing and thus keeps them fresher longer.
Unpack flowers purchased from a florist as soon as you receive them. If you are cutting your own flowers, cut them with a pair of sharp bypass pruning shears at a 45-degree angle. Then place each stem into a bucket filled with enough warm (roughly 110 degrees Fahrenheit) water to cover the stems almost all the way up to the flower heads.
Pull off or prune any leaves that will be underwater when the flowers are placed in their vase.
Place the flowers into a bucket filled with enough warm (roughly 110 degrees Fahrenheit) water to cover the stems almost all the way up to the flower heads (garden cut flowers can remain in the any small bucket used in Step 1) and then prune off the bottom inch of the stem at a 45-degree angle while it is still under water to prevent the formation of air bubbles. Add a packet of flower preservative (easily found at any florist) and leave the stems to soak overnight.
Place the flowers into a vase filled with room temperature water to which a packet of flower preservative has been added. Change the water every few days (add another packet of flower preservative each time) and store the flowers out of direct sunlight to further extend their life.