I have a flowlayout as follows:

I need to center all the controls on t
I'd go with TableLayoutPanel instead:
Fill to panelAutosizeFill to every button, except last oneTop to last buttonBTW in your solution you should iterate over flowLayoutPanel controls instead of form controls. Also consider subtracting horizontal margin and padding from width:
foreach (Control control in flowLayoutPanel.Controls)
{
control.Size = new Size(flowLayoutPanel.Width - control.Margin.Horizontal,
control.Height);
}
But I advise you to use TableLayoutPanel instead.