You shouldn't try to send fresh flowers by mail yourself, but there are companies that do ship arrangements by mail. You could ship pressed flowers, though.

www.flowers.com This is where I but all of my flowers online. They are great to work with and there finished pieces are breathtaking. I would recommend them to anyone.

Flowers Direct in the United Kingdom offers its patrons the ability to purchase flowers and ship them to wherever in the United Kingdom that they wish.

Its possible but need proper packaging

a u.s ship had about 900 people and the throw flowers at the wreak sight