Why do I get lowercase letter on formatting datetime?

I have a model with a datetime prop:

[DataType(DataType.Date)]
[DisplayFormat(DataFormatString = "{0:f}", ApplyFormatInEditMode = true)]
public DateTime? Date { get; set; }

in view I show it like this:

<p>@Html.DisplayFor(modelItem => Model.Discussion.Date)</p>

in the page it shows like this:

mandag 26. juni 2017 09.28

I want the day and month to start with big letters like this: Mandag 26. Juni 2017 09.28

What am I doing wrong?