My young sister passed away last good Friday and am wondering if taking flowers to her grave is OK as a christian

Hello, I believe you can. My opinion is you don't have to care if your christian, catholic, mormen, etc. Do not worry what society will think of you. If you would want to bring your sister flowers, than let it be. Oh, and I am so sorry for your lost.

Yes, putting flowers on the grave is a common custom in Christianity

Of course you can. Showing love and respect for someone you've lost is never a bad thing.

I am really sorry for the loss friend. It is really difficult to tolerate. Only God can give the peace which can really comfort you and your family members.

About your question, I think flowers for the grave of your loved ones is just an expression of your love. So it is OK.