A POLL says voters are largely in the dark about the Australian Greens.

According to the Essential poll, almost 50 per cent of people are unable to express an opinion on the performance of its leader, Tasmanian Senator Christine Milne.

The poll also showed 33 per cent of voters disapproved of the job Senator Milne was doing as Greens leader.

But 47 per cent said they didn't know, leaving only 20 per cent approving of her performance.

That contrasts to former leader Bob Brown's last approval rate of 42 per cent before he stepped down in April.