Answers for "expand column in flutter vertically"

flutter column widget vertical center

Column(
  mainAxisAlignment: MainAxisAlignment.center,
  crossAxisAlignment: CrossAxisAlignment.center,
  children:children,
)

flutter column vertical direction

Column(  
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisAlignment: MainAxisAlignment.center,
        verticalDirection: VerticalDirection.down,
        textBaseline: TextBaseline.alphabetic,
        textDirection: TextDirection.ltr,
        mainAxisSize: MainAxisSize.max,
        children: [
          Text('Column 1'),
          Text('Column 2')
        ],
      ),