CalendarDatePicker
The CalendarDatePicker control allows the user to pick a date value using a calendar. It's similar to DatePicker, except it displays a calendar instead of combo boxes.
Examples
Custom placeholder
The placeholder (the text that appears when the input is empty) can be changed using the Watermark property.
<CalendarDatePicker
Watermark="01/01/1970" />
Custom date format
The format of the date displayed can be customised by setting the SelectedDateFormat to Custom and providing a custom format in CustomDateFormatString in the same way DateTime.ToString(string format) accepts.
<CalendarDatePicker
SelectedDateFormat="Custom"
CustomDateFormatString="yyyy-MM-dd" />
This code will display the selected date in ISO 8601 format (year, month and day, separated by hyphens).
Remarks: Updating the date format won't change the displayed placeholder. That must be customised manually.