What should Grandmother of the groom wear?

am the mother of the groom and I am wearing a floor length dress, as is the mother of the bride, for a 2:00 pm wedding. The grandmother of the groom asked me if she could wear a floor length dress also but I did not know what protocol was for grandmothers. Any help? Thanks!

Carolinavic

Rebecca Black, Etiquette By Rebecca

Dear Carolinavi,

Floor length is usually fairly formal, so hopefully this wedding is. If not, you two might want to dress less formally.

Grandmother don’t usually dress as formally as the mothers. So, her dress would be slightly more formal than the average guest and less formal than the mothers. It would be best if her dress is not long. But, length is only one aspect of formality. If the dress is less formal than yours, it might be all right. You might have to call this one from your end.

Best wishes,