To keep cut flowers fresh for a longer period of time, start with a Clean Vase. Add warm water to the vase and then add 1 tbs of sugar and 1 tbs of Vinegar to the vase. Completely mix the water in the vase. Remove any leaves that would otherwise go below the waterline.
Get hold of clean pruning shears. Recut the stems at a 45-degree angle for maximum exposure. Add a copper penny to the vase. Do not place the cut flowers in direct sunlight, normal room light is sufficient for flowers. Change the water every other day and re-cut the stems each time.