How to make cut flowers last a week

Cut flowers die of thirst, not age. Everything below is about keeping water moving up the stem.

Trim two centimetres off the bottom at an angle. A flat cut sits against the base of the vase and seals itself; an angled one cannot. Air drawn in during the seconds a stem spends dry is what makes a rose droop at the neck two days later.

Strip every leaf that would sit below the waterline. Submerged leaves rot within a day, and the bacteria they feed block the stems of the flowers beside them.

Change the water every second day rather than topping it up. Topping up dilutes the bacteria; it does not remove them. Rinse the vase while you are there — the film on the glass is the problem.

Keep them away from three things: direct sun, the top of a fridge, and a fruit bowl. Ripening fruit gives off ethylene, which tells a flower it is time to finish.

What does not work, despite what you have been told: aspirin, copper coins, bleach in any quantity you would guess at, and lemonade.