Some ways to keep the flowers live for longer include cutting the ends off the stem. To do this, you require a sharp knife to avoid smashing the stem capillaries. You need also to remove any foliage from the stems that will be below the water line. You can also get a mixture of equal amounts of water and soda, which you can use to place the stems in. Read http://www.rd.com/home/8-ways-to-make-flowers-last-longer/.