 <p>Don't know if it is steel relevant but here is the solution:</p> <pre><code>TextBox _textBox; protected override void SetupEditControls() { base.SetupEditControls(); _textBox = (TextBox)EditControl; var value = CustomerTypeBox.Value ?? string.Empty; if (String.IsNullOrEmpty(value.ToString())) { _textBox.Text = "Default text"; } else { _textBox.Text = value.ToString(); } if (_textBox != null) EditControl.Parent.Controls.Add(_textBox); } public override void ApplyEditChanges() { var customerTypeBoxValue = _textBox.Text; if (customerTypeBoxValue != null) { SetValue(customerTypeBoxValue); } } </code></pre> <p>Default value for property is also possible to set in admin mode.</p>