I think it would be okay when writing poetry or something similar to say something like; I will put you in my heart, so I never lose you, or, I will put this memory in my heart so I never forget. However as dancingbear has rightly explained, if your meaning is 放在心上, we say take something to heart. 'Bear in mind' has nothing to with the heart and means to take something into consideration or to remember something when you are planning something else.

Bear it in mind.

你的意思是不是怎么把“放心”翻成英文？ 英文的意思是relax, feel relieved. 虽然我们不说"put something in heart"但是我们说 to take to heart 意思是“放在心上”。 她不把我们的警告放在心上。 She did not take our warnings to heart. 别把它放在心上。 Don't take it to heart.