Harding turned in a pass from Jason Puncheon after 25 minutes to help Southampton record their seventh successive home win.
Southampton should have scored many more goals in a one-sided first half but they spurned several clear chances.
"This was a good professional performance, vibrant and refreshing in the first half and resilient in the second when Leeds inevitably came back at us," said Pardew. "We are as good a side as any in this division but we have to prove we are the best in what remains of the season.
"We have the best playing surface and so many other advantages and there is a lot more to come from what is essentially a young side."
Source: Team Talk
Source: Team Talk