"One of the most asked questions is: why poppies? The answer is simple: poppies only flower when everything else in the neighbourhood is dead. Their seeds can lie on the ground for years and years, and only when there are no more competing flowers or shrubs in the vicinity (for instance when someone firmly roots up the ground), these seeds will sprout.
There was enough rooted up soil on the battlefield of the Western Front; in fact the whole front consisted of churned up soil. So in May 1915, when McCrae wrote his poem, around him poppies blossomed like no one had ever seen before. "

My Veterans Day contribution. In Canada, its called Remembrance Day and everyone wears poppies.