Добавьте ссылку на System.Windows.Forms и WindowsFormsIntegration в ваш проект
xmlns:WinForms="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
xmlns:WindowsFormsIntegration="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration"
И поместите в окно хост формы Windows.
<WindowsFormsHost Name="wfhDate"
HorizontalAlignment="Center"
VerticalAlignment="Stretch">
<WinForms:FlowLayoutPanel/>
</WindowsFormsHost>
Теперь в коде C #
using Forms = System.Windows.Forms;
.........................
Forms.FlowLayoutPanel flpPanel = this.wfhDate.Child as Forms.FlowLayoutPanel;
// Initialize your Forms contol here.
flpPanel.Controls.Add( yourControl );