According to custom , the mistletoe must not touch the ground between its cutting and its removal as the last of Christmas greens at Candlemas ; it may remain hanging through the year , often to preserve the house from lightning or fire , until it was replaced the following Christmas Eve . . According to custom , the mistletoe must not touch the ground between its cutting and its removal as the last of Christmas greens at Candlemas ; it may remain hanging through the year , often to preserve the house from lightning or fire , until it was replaced the following Christmas Eve .