The science of keeping cut flowers fresh

WASHINGTON — Valentine’s Day sees the year’s most frenzied rush on cut flowers, which begs the question: What’s really the best way to keep cut flowers looking good the longest in the vase?

Here’s the best advice we can offer, cobbled and condensed from dozens of peer-reviewed articles on cut flower preservation.

  • Wash the vase well first; starting out with a clean container is essential to long life.
  • Mix one can of non-diet Sprite or 7-Up lemon-line soda with three cans of distilled, filtered or spring water (not city tap water). Then add a few drops of vinegar.
  • Warm this mixture to around 100 degrees. That’s “warm,” but not “hot.” You want to feel the warmth but be able to keep your fingers in the water without scalding them. Whatever you do, don’t bring it to a boil.
  • Remove any leaves that would otherwise go below the water line.
  • Recut the stems at an angle and quickly place them in the still-warm water in the clean vase, but then immediately display the vase in a cool place. You want the warm water to convey sugary nutrition to the newly-cut stems, but the actual flowers to be as cool as possible.

To directly quote the researchers, from a paper published in 2013 in “The International Journal of Biotechnology and Molecular Biology Research,” who perfected the warm-water/cool room technique: “In this brief period [the first hour after the warm vase is moved to the cool location], the flowers will take up almost as much water as in the balance of their life.”

  • Do not display cut flowers of any kind near a heat source or in your warmest room. The cooler it is, the longer they’ll last — that’s why a good florist keeps his cut flowers in a refrigerated case.
  • Display cut flowers in normal room light. No direct sun!

Get everything right and we’re talking 16 days of beautiful bloom!

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