The best thing you can do for flowers is to keep them in a clean vase with fresh water, says Peter Grontas, owner of Flowers of the World in New York City.

DO: Chop off the green

Remember to trim excess greenery from flowers and don’t let any of the leaves fall below the waterline. This helps to keep the water clean and also prevents leaves from taking much needed water away from the blossoms.

DO: Trim daily

Cut the flowers’ stems immediately before putting them into the water, says Grontas. Most flowers need to have their stems cut periodically, as well. Grontas recommends cutting stems ¼ inch to ½ inch every one to two days because this helps flowers absorb fresh water.

DO: Add bleach

Adding a very tiny dollop of bleach, says Grontas, is the key to keeping bacteria out of the water, and keeping bacteria out makes blossoms last longer.

DON’T: Overdo it

Too much bleach will burn the stems and kill the flowers.

DO: Feed them up

Flowers thrive on proper floral food, says Julie Mulligan, an expert floral designer for 1-800-Flowers. Be sure to read the instructions to know what temperature water your flowers will prefer.

DON’T: Treat for headaches or bad breath

Forget that old myth about using aspirin or Listerine. According to Grontas, neither provide any nutrients and “they’ll only contaminate the vase by filling it with bacteria.”

DON'T: Give them an allowance

Will dropping a penny in the water strengthen the flower’s stem like our Aunt Gertrude taught us? Mulligan says while a penny might prevent a flower from drooping, it won’t help it last longer.

DO: Give 'em some sugar

If you are in a hurry for your flowers to open, you can put a little sugar in the vase, which Grontas says will speed the rate of blossoming. Putting the flowers in a warm room will also do the trick, though anything you do to speed the opening may also hasten the flowers’ demise.