A court in the Western Cape region ruled in March that a ban on cannabis use by adults at home was unconstitutional, effectively decriminalising it in the province that includes Cape Town.
The ruling hasn't however, said how much a person can legally have, and that will be up to parliament.
"We have used cannabis to treat anxiety, colic in children and as an antiseptic in secret for many years", said Phephsile Maseko, of the Traditional Healers Organisation.
The Constitutional Court will on Tuesday be handing down judgment on the question of whether or not to decriminalise cannabis use.
It will, however, remain illegal to use cannabis in public, and to sell and supply it.
South Africa is a large source of herbal cannabis for the United Kingdom and continental Europe.
The court upheld a decision made the Western Cape High Court previous year which ruled that personal use of marijuana should be legal.
Marijuana advocates and members of South Africa's Rastafarian community went into wild jubilation after the judgment.
The Constitutional Court's ruling focuses on the issue of privacy, and a person's right to do as they please in their own home.
The court has not approved - in any form - the trade in marijuana, meaning the government will not be able to profit from taxing a legalised industry.
Parliament would have to decide on this, it said.
It suspended its order of invalidity for a period of 24 months to give Parliament an opportunity to correct the constitutional defects in the two acts.
The unanimous judgment decriminalises adults smoking dagga at home and growing enough marijuana for personal consumption.