Hanami, a tradition unique to Japan ?

[Maciamo]

Hope this is enough data about how hanami was born

But that does not answer my question. Europeans have been writing poetry about the blossoming of trees and flowers earlier than the Heian period, and still do (while the Japanese are still taught Heian-era poens at school, as it seems they aren't many modern poets choosing that topic). Doing a Google search, I found several European poets writing about cherry blossoms too.

...
And in the warm hedge grew lush eglantine,
Green cowbind and the moonlight-colour’d May,
And cherry-blossoms, and white cups, whose wine
Was the bright dew yet drain’d not by the day;
...