@Html.EditorFor( model => model.StartDate )

@Html.EditorFor( model => model.StartDate.ToShortDateString() )

public class MyViewModel
{
    [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
    public DateTime StartDate { get; set; }

    ...

}

@model MyViewModel
...
@Html.EditorFor(model => model.StartDate)