too late to be useful; a day late and a dollar short
Idiomatic expression referring to something that arrives or is done after the opportunity has passed, like an iris blooming one day after the Boy's Day festival when it is no longer needed.
See also: 端午の節句
彼の助言は六日の菖蒲だった。
His advice came too late to be of any use.
Telling me that now is a day late and a dollar short.