Why do you need to cut flowers under running water?
Answers:
it is best to cut flowers under water (don't think it has to running, sounds to lazy to get a bucket).
if air gets into the xylem vessels they will not function any more and they won't transport water any more. Same as if you use a pump, if you trap air in the hose it will become less efficient or stop working.
A plants has many xylem vessels, but the more you keep working the better is the chance that your flowers stay fresh for longer.
For the same reason it can be a good idea to cut the stems of your flowers a bit shorter after a couple of days.
Other answers:
The reason why florists cut flowers under water is to "extend" the vase life of the flowers. But, that practice is slowly disapearing. Running water won't do the trick. Most florists don't cut underwater anymore beacause it is counter productive. You have to change the water after every bunch cut beacause the water must be completely clean and fresh. Cutting flowers underwater can actually make flowers die quicker if fresh water isn't used.
:) Ms. Orchid
The reason why florists cut flowers under water is to "extend" the vase life of the flowers. But, that practice is slowly disapearing. Running water won't do the trick. Most florists don't cut underwater anymore beacause it is counter productive. You have to change the water after every bunch cut beacause the water must be completely clean and fresh. Cutting flowers underwater can actually make flowers die quicker if fresh water isn't used.
:) Ms. Orchid
At home it is okay to do; to prolong the vase life, because yes, air gets up into the stems. Florists use another system now: We dip them in a special solution after we cut the flowers so that the stems uptake water faster. This way they last super long. We also do many other things to condition our flowers to make them last longer. (I can't tell you all our secrets :-) Hope that helps!