The two farm workers, aged 28 and 15, have admitted beating him to death in a dispute over unpaid wages, police say.
There is a heavy police presence outside the court in the north-western town of Ventersdorp, after the killing raised racial tensions in the country.
Members of Terreblanche's paramilitary AWB organisation are also there. They refuse to speak to black journalists.
The AWB - Afrikaner Weerstandsbeweging or Afrikaner Resistance Movement - on Monday retracted its initial threat to take revenge for Mr Terreblanche's killing.
However, it blames ANC Youth League leader Julius Malema for contributing to the killing by recently singing a song from the anti-apartheid struggle called "Shoot the Boer".
Boer is an Afrikaans word for farmer, which has become a derogatory term for all white people.
Mr Malema has denied any responsibility for Mr Terreblanche's death and the ANC argues that the song does not incite people to kill but is part of the country's history and the fight against white minority rule.
It is planning to appeal against a court judgement banning the song as hate speech.
The authorities are keen to stress that the killing appears to be a criminal, rather than a politically motivated, act.
President Jacob Zuma has appealed for calm and condemned the killing.
Mr Terreblanche, 69, was fiercely opposed to the end of apartheid in South Africa, which led to the ANC winning the country's first democratic elections in 1994 and Nelson Mandela becoming the country's first black president.
He served three years in jail after being convicted in 2001 of the attempted murder of a farm worker.
He is due to be buried on Friday.
BBC News
