Peonies are not high-maintenance divas. Despite their gorgeous blooms, peonies, once established in the garden (they need a few years), are easygoing. Peonies relish cold winters, because they need chilling for bud formation. They are native to Asia, Europe and Western North America.
To ensure long life cut/buy them while they are still in bud and just barely beginning to open. If you get peonies that are already fully open, they will look gorgeous but will only last a few days at most.
After you bring your flowers into the house, fill your clean vase one-third full with lukewarm water. Remove all the leaves that would be under the water level. Every three days clean and refill the vase with fresh lukewarm water. Recut the stems under water, snipping off about 1 inch from each one.