How to handle long text in InputDecoration->labelText in Flutter

Question

I have a TextFormField in Flutter setup, like this:

new TextFormField (
    decoration: new InputDecoration(
    labelText: questionString,
    labelStyle: new TextStyle(
      fontSize: 18.0,
      color: new Color(0xFF18776A),
    )
),

This generates the following screenshot:

The text is cutting at the end automatically because is too long. Is there a way to adjust the font size to fit the screen or make labelText expand to two lines?