Speaking with Guardian editor Alan Rusbridger at a session on online journalism on Sunday, Georgina Henry said Comment Is Free was growing more quickly than the US writers' network on which it is modelled, Huffington Post.
"Nine months in, they were up to about 500 bloggers; we're up to about 500 bloggers after two months," she said. "We've put up about 1,400 pieces on the blog, another 1,200 pieces from the paper.
"When I started this, I did look on it as a newspaper journalist; these were things that we were putting up that you had to read. I didn't really get the measure of the conversation that goes on.
"Two months on, I'm kind of humbled by it. You have to think in a different way about what exactly does divide your professional columnists and the people that I recruited to blog from the readers, who are sometimes extremely erudite."
Ms Henry said abusive comments from readers were moderated but that care was taken to keep the site "fair and free", and she responded to recent concern about Comment Is Free's contributor payments policy, which rewards popular and hand-picked bloggers.
"The deal is, they are invited to blog as and when they want; they have freedom," Ms Henry said.
"In exchange, I don't really pay them - it amazes me, the number of people who just want to have a debate about stuff and actually money isn't the primary thing [for them]. We pay if we commission you directly and if we make you the pick of the day."
Mr Rusbridger conceded payments were "a pittance" but suggested it was crucial to involve the blogosphere in discussions supported by the Webby award-winning newspaper.
"What we're doing, which no newspaper has ever done before, is to take your elite stable of columnists, who are paid, and pitch them into the same space as people who aren't paid," he said.
"What is professional journalism and what isn't, and how do they share the same space? We're making this up as we go along."
Future Comment Is Free developments are likely to include the ability for readers to rate each other's comments, the pair said.