The Black Cats have struggled to find a cutting edge so far this term, having scored just six this season, with Demba Ba's own goal in the 1-1 draw with Newcastle their only strike in over a month.
However, the 60-year-old believes Gardner has the potential to add more to their tally, suggesting he should be hitting double figures on a consistent basis.
"I feel that Craig should have 10 league goals at the end of every season - regardless of the number of games that he plays," the former Aston Villa boss told reporters.
"When I say 'regardless of the number of games that he plays', I mean of course assuming he plays upwards of 25 of course. It would be asking a bit much if he only played eight or nine times!
"But Craig's eye for goal really could be a tremendous asset for us.
"He has got a great shot, he gets into dangerous positions and he hits the ball as strongly and as truly as anyone in the Premier League."
The 25-year-old managed 10 goals in his final season at Birmingham, before moving to the Stadium of Light for £5 million two years ago.
However, he recorded just three goals last season, and has found the net once so far this campaign, the effort coming against MK Dons in the Capital One Cup.
A large factor in that, though, has been the injury to Phil Bardsley, which in turn has seen Gardner fill in at right-back for the North East side.
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The Northern Irishman added: "Playing at full-back, he was unable to get into those forward advanced midfield positions but now he is back in midfield, I will be looking for him to contribute some goals.
"We need goals from other sources, we know that. Steven Fletcher has made a very good start since joining us in the summer but we can't put all the goalscoring burden on one man. Other players have to share the load.
"At the moment we are just not creating enough chances and that needs to change. We know that, we recognise it and we are working hard to find ways of improving it."