The Green Party has hit a major milestone this week, reaching 175,000 members — a level of support the party has never come close to in its modern history.

It marks a stunning surge under Zack Polanski, who became leader only a short time ago and has already overseen one of the fastest periods of membership growth ever recorded by a UK political party outside of a general election.

A membership explosion few saw coming

Before Polanski took over, the Greens were hovering below 70,000 members. Fast-forward to today and the party has added well over 100,000 new members, with sign-ups accelerating every week.

People inside the party say the pace has been “like nothing we’ve seen before”, with local branches scrambling for bigger rooms, extra volunteer organisers and new digital systems just to keep up with the flood of joiners.

For a party that has long struggled for national visibility, this moment feels different. Not only is the membership booming — they’re also climbing the polls.

Greens in second place nationally

A recent UK-wide poll put the Greens on 17%, pushing them into second place and cementing their status as the country’s fastest-growing political force.

For years, the Greens were dismissed as a niche party focused mainly on climate issues. But under Polanski, they’ve broadened their pitch — talking about housing, workers’ rights, the NHS, and the cost of living — while keeping climate at the centre. That combination appears to be landing with voters who feel ignored by both Labour and the Conservatives.

Why the rapid growth matters

The Greens have always had passionate supporters, but size matters in politics. More members means:

• More volunteers on streets and doorsteps

• More money coming in to fund campaigns and organisers

• More candidates standing locally and nationally

• More pressure on Labour to stop assuming it has the left to itself

Crucially, this kind of momentum has a snowball effect. When a party looks like it’s moving somewhere, more people want to be part of it.

The Polanski factor

Supporters credit Polanski’s leadership style — energetic, outspoken, media-savvy — with giving the party a sharper national profile. His willingness to challenge both Labour and the Conservatives head-on has helped the Greens feel less like a fringe voice and more like a serious political alternative.

And members seem energised by it. One local organiser in the Midlands put it bluntly:
“People aren’t joining because it’s trendy — they’re joining because they think the Greens can actually change things.”

A turning point for the Greens?

Whether the Greens can turn 17% in the polls into Westminster seats remains the big question — the electoral system still works heavily against smaller parties. But there’s no doubt this is a watershed moment.

A party that once struggled to break through is now signing up members in record numbers, climbing the national polls, and shaping the political conversation in a way few would have predicted even a year ago.

For Polanski and the Greens, 175,000 members isn’t just a statistic — it’s a signal that a significant chunk of the country is looking for something different, and believes the Greens might just be the ones to deliver it.