The party made a historic breakthrough last election when it elected climate scientist Andrew Weaver in a riding previously held by a provincial cabinet minister, but Sterk lost her own riding by more than 3,000 votes.
Sterk, who was elected leader in 2007, originally agreed to stay on. But on Tuesday she said her decision to resign has been a long time coming.
"We've had three months since the election," she said in an interview, adding she's since reflected on what she wants "to do personally and where the party (is) at."
"It just seemed like perfect timing on both counts."
Sterk announced the decision on Twitter, telling her 2,200 followers that she had a good run, but she had reached her best-before date and was looking for a new adventure.
"I'm at an age where if I want to do something new, I better get on with it," she said, laughing.
Sterk said she'll formally resign at the party's annual general meeting on Aug. 24.
As for her replacement, Sterk said she expects Weaver will put his name forward as he's likely the most logical choice.
"If the party was able to attract some really high profile candidates who might contest the leadership, that would bring a level of interest and energy into the party," she said. "But at the moment I think that we have an elected MLA and he would be a person that I hope to see put his name forward."
Weaver was travelling outside the country and did not respond to a request for comment.
Sterk said she's proud of the changes she's made to the Green Party since she became leader, especially her "business-like orientation."
"We are a party that doesn't go into debt and I think we're the only party that works on that basis, from a fundamental belief that we need to live within our means," she said.
But Sterk said she deeply regrets "not getting elected."
"I think that (B.C. is) going down a road towards serious crises on virtually every front. We already know we have a democratic crisis in terms of lack of participation and lack of belief (among) the citizenry that they can impact the public policy decisions that are made. But we also have an ongoing economic crisis, we have a climate crisis which nobody is talking about, and we have social crises where we're not able to deliver the kinds of services that people want where they need them," she said.
"My worry is that, with our current political orientation, that we'll have to get into pretty significant crisis before politicians behave differently."
NDP leader Adrian Dix said he is very appreciative of Sterk's contribution to politics.
“Our politics is healthier when more British Columbians see their voice reflected in our public debate," he said in a statement.
"Jane's contribution attracted many who might otherwise have forsaken party politics."
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