put sb. out to grass 的意思是“解雇；使退职（尤指因年老）；迫使（年老者）退休；让某人离职”。

【例句】
He's too old to work fast, so his employers have put him out to grass.
他年纪太大，干活不快了，所以他的雇主们就叫他退职了。

My grandmother was put out to grass when she was near 60.
我祖母在将近60岁的时候被解雇了。