Cut flower food

Since there are a few chemists here I wonder if anyone know what is the sachet of salt that come with cut flowers that suppose to make them last longer. Are they toxic to human if ingested? Done a quick google and this website suggest a homebrew substitute is a mix of sugar, aspirin and bleach. If that is all it is then there is no need to worry and could be a money saving tip too.

http://www.marthastewart.com/page.jhtml?type=content&id=channel172185&catid=cat379

 

Dont know jack about cut flowers, but when i did my tree surgeory college stint we did a fair bit of biology. Most plants require phosfates, nitrates and potassium.
AFAIK most plant food are not toxic to people, wouldn't recomend eating though.
No idea about the home brew idea, aspirin and bleach for plants just sounds not right to me tho

 

we had some cut flowers in the kitchen for what seem like like weeks - they are bionic

 

Penance,
If they are just a collection of sugar and salts then it should not be toxic. I thought the aspirin and bleach suggestion seems reasonable but given there is no measurement given with the recipe it is not really helpful.

Given that some of the cut flowers seem to last longer then it use to be, which is just a subjective observation, I wonder if it is due to the plant food.

 

my googling says either aluminium sulphate, or concentrated citric acid.