How to preserve cut Dahlia Flowers out of a week?

[abodelook]

My neighbor has just brought me a huge bunch of Dahlia Flowers which are much too pretty to spoil after three days. I have gotten the plant care manuals at abodelook knowledge hub, but wonder whether you all have any insider tricks. I have heard all about adding a drop of bleach to the water to the use of the lukewarm tea that makes these blooms stand straight and stay wet?