When he was grow older.
When he grew older.
什麼時候用was 什麽時候不用？

應該是 when he has grown older
以上was 不是past tense (過去式)
也可以寫成when he was getting older
寫成這樣就也不算過去式

2# omitrix
應該要翻一下文法書when的句子不可用現在完成式吧!

as i know
When 或What time 開頭的句子，不用現在完成式。
例句:
When did you visit New York?（○）
When have you visited New York?（×）