Natalie Bennett says Greens are only alternative
Party leader Natalie Bennett has told supporters the Greens are the only alternative to the "indistinguishable" big Westminster parties.
She predicted a change in British politics as voters look to parties like hers and UKIP for "new answers".
The party is training activists at its annual conference in Brighton how to emulate UKIP's recent success.
In her speech, Ms Bennett attacked the coalition over the economy and Labour for not providing an alternative.
"There is one alternative to the three virtually indistinguishable neoliberal parties," she told party members.
"That alternative is the Green Party."
The Green Party in England and Wales want to ban all advertising aimed at children and plan to set out proposals to boost the economy and end food poverty.
They will use the conference to discuss how to tackle fuel poverty and oppose the privatisation of the NHS and Royal Mail.
Ms Bennett said the health service was being "torn to shreds" and "handed over to handful of profit-at-any-costs, multinational health companies."
To applause and cheers she told supporters: "We will not rest until we've expelled every last corporate blood sucker from our NHS."
BBC political correspondent Chris Mason said the speech was "defiantly and proudly left-wing in tone".
But on Saturday, the conference will discuss what it can learn from an unlikely source.
A session is scheduled on how the Greens can "break into mass popular awareness" in the way that Nigel Farage's UK Independence Party managed in May's local elections, when it gained 139 councillors.
Voters now talk about UKIP and the Greens "in the same breath", Ms Bennett told BBC Radio 4's Today programme earlier.
"Obviously our politics are very different. But people are looking for new answers and we're going to see big shifts in British politics in the next few years."
The party is also running "election boot camps" for candidates and activists at its conference in an effort to increase success.
The Greens gained five council seats at this May's local elections in England but the party has failed to make a breakthrough, except in Brighton and a handful of other areas in England.
Former leader Caroline Lucas has been MP for Brighton Pavilion since 2010 and the party has run Brighton and Hove City Council as a minority administration since 2011.
She told the BBC's Daily Politics programme the party could triple its tally of MEPs in next year's European elections, from two to six.
Ms Lucas said the conference was the party's chance to encourage people to vote Green in the elections "if they want a safer environment and a fairer social system".
Party leader Ms Bennett, a former journalist who took the reins last year, predicted the government would have to reverse its policy on fracking.
The Greens have been prominent in the protests against the controversial drilling for shale gas.
"If we go for the 'dash for gas'... we're going for a really high-cost, uncertain energy future," she added.
She used her speech to pay tribute to her predecessor, inviting delegates to applaud Ms Lucas before she started her address.
The Australian-born leader hit out at the Lib Dems for failing "to protect Britain from the Tories" and was scathing about Labour's positioning on benefit cuts, public spending and immigration.
Turning to international affairs, she called for a diplomatic solution to the Syrian crisis.
"Russia and China are not easy partners, but the legal way forward... is the only way forward," she said.
But the bulk of the speech focused on social and economic policy.
She called for more help for small and local businesses and promised to campaign until foodbanks were no longer needed.
"Volunteering shouldn't be about providing the essentials of life because the government is failing to do so."
Poverty was a theme returned to by Ms Lucas when she took to the stage later.
"We have a government that is intent on demonising the poor and vulnerable," the party's first and only MP said. "This is worse than the Victorian era."