How to keep roses fresh for two weeks (really)

A rose stem is a straw with a blockage problem. The moment it is cut, air rushes into the xylem and forms a lock that stops water reaching the head. Everything that follows is about clearing that lock and keeping it clear.

Re-cut every stem at 45 degrees, ideally with the stem held under running water. A diagonal cut stops the end sitting flat against the vase base, and cutting under water means no fresh air pocket forms.

Change the water every two days without exception. Bacteria in cloudy water block the stem far faster than any lack of nutrients. If you skip the flower food, a teaspoon of sugar and a drop of bleach does most of the same work.

Strip every leaf that would sit below the waterline. Submerged foliage rots within a day and turns the vase into a bacterial culture.

Finally, placement. Roses last longest somewhere cool, out of direct sun, away from heaters and nowhere near a fruit bowl — ripening fruit releases ethylene, which tells a flower it is time to finish.