How can cut flowers be made to last longer in a vase?

The BEST way to keep cut fresh flowers longer is to retrim the stems of the flowers, if in a vase and replace the water every other day. If the flowers are in foam, or centerpiece keep the foam well watered until the flowers die. Some flowers like roses need special care to keep longer then say carnations and daisies. Roses need the stems trimmed under running cool water NOT COLD and trim ends about 1/8 inch put in fresh water always cut on an angle and you can put a portion of 81mg aspirin in the water but they make a packet called flower fresh and that works better! Daisies and carnations trim ends on an angle above or below a joint and put in clean cool water when the vase starts to turn color or smell bad they should last a lot longer than roses!

You can also use salt sugar flower anything like that.