They all claim he was against public unions - but that's not true. He was against strikes by public employees, but not against their unions. Here's what he really said:
"Particularly, I want to emphasize my conviction that militant tactics have no place in the functions of any organization of Government employees. Upon employees in the Federal service rests the obligation to serve the whole people, whose interests and welfare require orderliness and continuity in the conduct of Government activities. This obligation is paramount. Since their own services have to do with the functioning of the Government, a strike of public employees manifests nothing less than an intent on their part to prevent or obstruct the operations of Government until their demands are satisfied. Such action, looking toward the paralysis of Government by those who have sworn to support it, is unthinkable and intolerable. It is, therefore, with a feeling of gratification that I have noted in the constitution of the National Federation of Federal Employees the provision that "under no circumstances shall this Federation engage in or support strikes against the United States Government.""
and:
"The desire of Government employees for fair and adequate pay, reasonable hours of work, safe and suitable working conditions, development of opportunities for advancement, facilities for fair and impartial consideration and review of grievances, and other objectives of a proper employee relations policy, is basically no different from that of employees in private industry."
Read here -
http://www.dailykos.com/story/2011/02/16/945416/-Whats-the-Deal-with-FDR-and-Public-Unions and scroll down to the comments.